b structured questions

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COLLECTION OFSTRUCTURED QUESTION

(2003-2008)


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Answer To Score Chemistry Structured Questions

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FORM 4 CHAPTER 2 THE STRUCTURE OF THE ATOM &CHAPTER 3 CHEMICAL FORMULAE AND EQUATION

ANALYSIS OF PAST YEAR QUESTIONS FROM 2003 2008

Year 2003 2004 2005 2006 2007 2008Paper

No.P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of

questionS E S E S E S E S E S E S E S E S E S E S E S E

Question

No1 1 1a 1

10a

10

b

1 2 93,

58 3

STRUCTURED QUESTION

1 SPM 2003 /P2/ Q1

Figure 1 shows the set-up of apparatus for an experiment to determine the empiricalformula of magnesium oxide.

Figure 1Result :Mass of crucible + lid = 24.0 gMass of crucible + lid + magnesium ribbon = 26.4 gMass of crucible + lid + magnesium oxide = 28.0 g

(a) What is meant by empirical formula?

[1 mark]

(b) Based on the above results,(i) Calculate the mass of magnesium and the mass of oxygen that have reacted.

[1 mark]

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(ii) Calculate the mole ratio of magnesium atoms to oxygen atoms[Relative Atomic Mass: O = 16, Mg = 24]

[1 mark]

(iii) Determine the empirical formula of magnesium oxide.

[1 mark]

(iv) Write the chemical equation for the reaction in this experiment.

[1 mark]

(c) Why was the crucible lid opened once in a while during the experiment?

[1 mark]

(d) Metal X is placed below hydrogen in the reactivity series. You are required to carryout an experiment to determine the empirical formula of the oxide of metal X. Theapparatus provided are combustion tube, glass tube, cork, Bunsen burner, andporcelain dish.

(i) Draw a labeled diagram of the set-up of the apparatus for the experiment.

[2 marks](ii) Describe the steps that should be taken to ensure that all the air in the combustion

tube has been expelled.

..

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[3 marks]

2 SPM 2004/ P2/ Q1(a) Table 2 shows four substances and their respective formulae

Substance Chemical formulaIodine I2

Copper CuNaphthalene C10H8Copper (II) sulphate CuSO4

Table 2Use information from Table 2 to answer the following equations

(i) State one substance from Table 2 which exists as a molecule.

[1 mark]

(ii) Which substance has the highest melting point, iodine, copper or naphthalene?

[1 mark](iii) What is the state of matter of copper (II) sulphate at room temperature?

[1 mark]

(iv) State the substance in Table 2 which can conduct electricity in the solid state.

[1 mark]

(v) Draw the arrangement of particles in the substance in (a)(iv)[1 mark]

(vi) Write the ionic formula for the substance in (a)(iv).

[1 mark]

(b) Graph 2.1 shows the temperature against time when solid naphthalene is heated

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Graph 2.1(i) State the melting point of naphthalene.

[1 mark]

(ii) Explain why there is no change in temperature from Q to R

[2 marks]

(iii) State how the movement of naphthalene particles changes between R and S during theheating.

[1 mark

3 SPM 2006/ P2/ Q2(i) What is the chemical symbol used to represent one water molecule?

[1 mark]

(ii) What is the name of the isotope od an element used as a standard in determiningrelative atomic mass?

[1 mark]

b(i) What is the mass of 6.0dm3 of carbon dioxide gas, CO2 at standard temperature andpressure?[1 mole of gas occupies 24 dm3 at standard temperature and pressure;Relative atomic mass for CO2 = 44]

[2 marks](ii) How many molecules are there in 6.0 dm3 of carbon dioxide gas?

[Avogadro number = 6.02 x 1023]

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[1 mark](iii) Explain briefly the relationship between the volume, mass and the number of

molecules of carbon dioxide in 3b(i) and 3b(ii) at standard temperature andpressure.

[3 marks]

4 SPM 2007 / P2/ Q3(a) What is the meaning of empirical formula?

[1 mark]

(b) Diagram 3.1 shows an incomplete equation which is one of the steps involved indetermining the empirical formula.Complete this equation.

Diagram 3.1[1 mark]

(c) Diagram 3.2 shows the apparatus set-up for two methods used to determine theempirical formula of two compounds.

Diagram 3.2

Based on Diagram 3.2, determine the values of the following:

[Relative atomic mass : O=16, Pb = 207 ]

(i) Mass of lead

7

Mass =

Relative atomic mass ..


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Answer To Score Chemistry Structured Questions= ..g

[1 mark](ii) Number of moles of lead

= ..g[1 mark]

(iii) Mass of oxygen

= ..g[1 mark]

(iv) Number of moles of oxygen

= ..g[1 mark]

(v) Empirical formula of lead oxide

= .[1 mark]

5 SPM 2007 / P2/ Q5Diagram 5 shows the symbols of the atoms of element X and element Y.The letter used are not the actual symbols of the elements.

Diagram 5

(a) State the proton number of the atom of element X.

[1 mark]

b(i) F4 Topic 4 : Periodic TableIdentify the position of element X in the Preiodic Table of Elements

[1 mark]

b(ii) Explain why element X is placed at the position identified in 5(b)(i).

[1 mark]

c(i) [Concept based on F4 Topic 4 : Periodic Table]The reaction between element X and oxygen is less reactive than the reactionbetween element Y and oxygen.Explain this using ideas about valence electron.

[2 marks]

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Answer To Score Chemistry Structured Questions(ii) Draw a labeled diagram to show the apparatus set-up that can be used to determine

the reactivity of the reaction between element X or element Y and oxygen gas.

[ 2marks]

(d) 2.3g of element X reacted completely with oxygen.The following equation represents the reaction.

4X(s) + O2(g) 2X2O(s)

[Relative atomic mass : X = 23, O = 16]

(i) Calculate the number of moles of element X.

[1 mark]

(ii) Calculate the maximum mass of X2O formed.

[3 marks]

6 SPM 2008 / P2/ Q3(a) Diagram 3.1 shows the results of an experiment to investigate the movement of

bromine particles in air.

9

Bromine vapourspreads

throughout bothgas jars within10 minutes

Gas jarAir

cover

Bromine vapour


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Diagram 3.1

(i) State the name of the process involved in this experiment.

[1 mark]

(ii) State the type of particle present in bromine gas, Br2.

[1 mark]

(iii) Explain the observation in this experiment based on the kinetic theory of matter.

[3 marks]

(iv) This experiment is repeated at a higher temperature.Predict the time taken for the bromine vapour to spread throughout the space in bothgas jars.

[1 mark]

(b) Diagram 3.2 shows two balloons containing oxygen gas and carbon dioxide gasrespectively.

Balloon A Balloon B

Diagram 3.2Based on the given information:

(i) Calculate the mass of oxygen gas in balloon A[Relative atomic mass : O = 16]

10

Cover removed

0.5 molCarbon dioxidegas, CO

2

0.5 moloxygengas, O

2


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[1 mark](ii) Calculate the volume of carbon dioxide gas in balloon B.

[Molar volume of gas = 24 dm3mol-1 at room temperature and pressure]

[1 mark]

(iii) Compare the number of gas molecules in balloon A and in balloon B.Explain your answer.

[2 marks]

7 SPM 2004/ P3/ Q1A student carried out an experiment to determine the empirical formula ofmagnesium oxide. The steps and set-up of apparatus of the experiment are shown inFigure 1.

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(a) Complete the following table by stating the observation and related inferences in theexperiment.

Observation Inferences

(i) ..

.

(ii) .

.

(i) .

.

(ii)

.[6marks]

(b) Record the reading to two decimal places for:

The mass of crucible and lid: g

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The mass of crucible, lid and magnesium ribbon : g

The mass of crucible, lid and magnesium oxide when cooled : .g

[3marks]ci) What is the mass of magnesium that has been used?

[3marks](ii) What is the mass of oxygen which reacted with magnesium?

[3marks]

(iii Determine the empirical formula of magnesium oxideUse the information that the relative atomic mass, Mg = 24 and O = 16.

[3marks]

(d) Based on your answer in (c)(iii), how many moles of magnesium and oxygen atomshave reacted?

[3marks]

8 SPM 2005 /P3/ Q1An experiment is carried out to determine the freezing point of naphthalene. Solidnaphthalene is heated in a water bath until it melts completely.The initial temperature is recorded.Then molten naphthalene is left to cool.The reading of the temperature is recorded every 30 seconds.Figure 1 shows the recorded thermometer readings at 30 seconds intervals.

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a) Record the temperatures in the space provided in Figure 1.[3marks]

b) On the graph paper below, draw the graph of temperature against time for thecooling of naphthalene.

[3marks]

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ci) Use the graph in (b), to determine the freezing point of naphthalene.Show on the graph how you determine this freezing point.

[3marks](ii) How does the graph in (b) show the freezing point of naphthalene?

[3marks]

(d) The temperature of naphthalene did not change from the 90th second until the 50thsecond during the cooling process.Explain why..

.[3marks]

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Answer To Score Chemistry Structured Questions(e) On the graph paper below sketch the curve you would expect if the molten

naphthalene is cooled quickly.

[3marks]

(f) Naphthalene is an example of a covalent compound and sodium chloride is anexample of an ionic compound.Classify the following into covalent or ionic compounds.

[3marks]

16

Glucose, potassium iodide, copper(II) sulphate,

Aluminium oxide, tetrachloromethane, ethanol


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CHAPTER 4 : PERIODIC TABLE OF THE ELEMENTS


Year 2003 2004 2005 2006 2007 2008

Paper No. P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type ofquestion S E S E S E S E S E S E S E S E S E S E S E S E

Question No 2 1 8

5a

5

b

5c

2 2

STRUCTURED QUESTIONS

1 SPM 2003/P2/Q2

Table 2 shows part of the Periodic Table of Elements.

Figure 2

Based on Figure 2, answer the following questions.a) What is the element represented by the symbol Fe?

[1 mark]

b) In figure 2, mark X in the boxes for all the transition elements.[1 mark]

c) State one specific characteristic of transition elements.

[1 mark]

d) Write the electron configuration for the Mg atom.

[1 mark]

e) i) Write the chemical equation for the reaction between aluminium and oxygen.

[1 mark]

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ii) Briefly state the electron transfer in the bond formation between aluminium andoxygen.

..

..

[2 marks]f)

Based on the above information, which gas is more suitable to be used inmeteorological balloons?

Give one reason.

..

[2 marks]

2 SPM 2005/P2/Q1

Figure 1 shows part of the Periodic Table of the Elements.Q, R, T, X and Y do not represent the actual symbol of the elements

Figure 1a) Using the letters in the Periodic Table of the Elements in the Figure 1, answer the

following questions.You may use the Periodic Table of the Elements on page i) Choose an element that is a halogen.

..[1 mark]

ii) Which element is monoatomic?

[1 mark]

18

Helium Gas

- light

- not reactive

- colorless

Hydrogen Gas

- light

- flammable

- colorless


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iii) Which element forms an amphoteric oxide?

.[1 mark]

b) Arrange Q, R, T, X and Y according to increase in size of the atoms.

.[1 mark]

c) Write the electron arrangement for an atom of element Q.

[1 mark]

d) Write the formula for the ion formed from an atom of element Y.

.

[1 mark]

e) Why are elements Q and R placed in the same period?

.[1 mark]

f) When a small piece of element T is put into water, TOH solution is formed andhydrogen gas is released.State one observation when red litmus paper is put into the solution.

...

[1 mark]

g) State the common name of the elements between group 2 and group 13.

[1 mark]

3 SPM 2007/P2/Q5

Diagram 5 shows the symbols of the atoms of element X and element Y.The letter used are not the actual symbols of the elements.

Diagram 5

a) State the proton number of the atom of element X

[1 mark]

b) i) Identify the position of element X in the Periodic Table of Elements.

.

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4 SPM 2008/P2/Q2

Table 2.1 shows a group of elements.

Table 2.1

a) In which group of the Periodic Table are these elements located?

[1 mark]

b) Write the electron arrangement for an atom of fluorine.

[1 mark]

c) Fluorine atoms are smaller than chlorine atoms.Explain why fluorine forms a negative ion more easily than chlorine.

..[2 marks]

d) State the type of chemical bond in an iodine molecule.

[1 mark]

e) Chlorine reacts with sodium to form a compound.i) State the type of chemical bond in this compound.

[1 mark]

ii) Draw a diagram to show the electron arrangement in this compound.[Proton number of Na = 11]

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Answer To Score Chemistry Structured Questions[2 marks]

f) Table 2.2 shows three pairs of chemicals.

Chemicals

KI (aq) + Cl2(aq)

KCl (aq) + Br2(aq)

KBr(aq) + KCl (aq)

Put a tick (/) in the box beside the pair of chemicals which will undergo adisplacement reaction.

[1 mark]

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CHAPTER 5 : CHEMICAL BOND


Year 2003 2004 2005 2006 2007 2008


Type ofquestion

S E S E S E S E S E S E S E S E S E S E S E S E

Question

No

1

b

1c

10c 3 4


1 SPM 2006/P2/Q3

a) i) The electron arrangement for argon is 2.8.8.Why is this element very stable and not reactive?

[1 mark]

ii) Name one other element that has the same stability as argon.

[1 mark]

b) Atoms of both sodium and chlorine are unstable.They react to form an ionic compound which is more stable.Diagram 3.1 shows a sodium chloride compound, NaCl, that is produced by theformation of an ionic bond between a sodium ion, Na+, and a chloride ion, Cl-.

Diagram 3.1

i) How are a sodium ion and chloride ion formed from their respective atoms?

Sodium ion : ..

Chloride ion : .[2 marks]

ii) Name the force that exists between these ions in the compound.

...[1 mark]

23

Na+ Cl-

-+


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iii) The melting point of sodium chloride, NaCl, is 801oC and its boiling points is1413oC.What will happen to the ions in this compound at 900oC?

[1 mark]iv) Give one reason for your answer in 3(b)(iii).

..[1 mark]

c) Diagram 3.2 shows the proton number and nucleon number for two elements, X and Y.The letter used do not represent the actual symbols of the elements.

Diagram 3.2

Draw a diagram to show the bonding formed between elements X and Y

[3 marks]

2 SPM 2007/P2/Q4Table 4 shows the electrical conductivity and melting points of substances P, Q and R.

SubstanceElectrical conductivity in the state of

Melting point/oCSolid Molten Aqueous

P No No No < -110Q No No No 80 90R No Yes Yes > 800

Table 4

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a) i) State the types of structure and bonding of substance P.Structure :

.Bonding :

.[2 marks]

ii) Explain why substance P has a low melting point.

.

[1 mark]b) State how the bonds are formed in :

i) Substance Q

.[1 mark]ii) Substance R

.

[1 mark]

c) State why the electrical conductivity of substance R is different in solid state comparedto the molten and aqueous states.

Solid state:

.

.[2 marks]

Molten and aqueous state :

.

.[2 marks]

d) Based on the information in Table 4, fill in the following blanks.

Substance . is soluble in water.

Substance and substance are insoluble in water[3 marks]

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F4 Chapter 6 ElectrochemistryF5 Chapter 3 Oxidation & Reduction


Year 2003 2004 2005 2006 2007 2008

Paper

No.

P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of


Question

No

F4 Chp 6

F5 Chp 3 5 3 3 4 2 6 9 2

1

0

76 2

8

9


1 SPM 2003/P2/Q5

Figure 5 shows the set-up of apparatus to investigate the reactions that take place intest tubes P and Q.

Figure 5

(a) State the observation for the reaction(i) in test tube P.

[1 mark]

(ii) in test tube Q.

[1 mark]

(b) Write the ionic equation for the reaction in (a)(i).

..[1 mark]

(c) State what is meant by oxidizing agent in terms of electron transfer.

..[1 mark]

(d) Referring to the reaction that takes place in test tube P,

(i) what is the change in the oxidation number of magnesium?

[1 mark]

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(ii) name the oxidizing agent.

[1 mark]

(e) Referring to the reaction that takes place in test tube Q,(i) state the type of reaction that occurs.

[1 mark]

(ii) state the oxidation number of bromine in bromine water.

[1 mark]

(iii) what is the function of bromine water?

[1 mark]

(iv) name another reagent that can replace bromine water.

[1 mark]

2 SPM 2004/P2/Q3Figure 3 shows the set-up of apparatus to investigate the electrolysis of dilutecopper(II) sulphate solution.

Figure 3

(a) (i) What is meant by cation?

....[1 mark]

(ii) What is the energy change that occurs in the electrolysis process?

[1 mark]

(b) In the electrolysis of dilute copper(II) sulphate solution:(i) State all the ions in the electrolyte.

[1 mark]

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(ii) In the table below, write the ions in (b)(i) which moved to electrodes X andY.

Electrode X Electrode Y

[1 mark](iii) What are the processes that occur at electrodes X and Y?

Electrode X :

Electrode Y : [1 mark]

(iv) What would you observe at electrode Y?

[1 mark]

(v) What is the colour change of the electrolyte?

[1 mark]

(c) (i) Name the gas collected in the test tube at electrode X.

[1 mark]

(ii) The volume of gas collected at electrode X is 20.0 cm3.How many moles of the gas were collected?Use the information that 1 mole of gas occupies a volume of 24.0 dm3 atroom temperature and pressure.

[1 mark]

(iii) Based on the answer in (c)(ii), what is the number of gas moleculescollected?Use the information that the Avogadro number is 6.02 x 1023 mol-1.

[1 mark]

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3 SPM 2005/P2/Q6Table 6 shows the descriptions and observations for two experiments, I and II.

Experiment Description ObservationI Electrolysis of 1 mol

dm-3

sodiumsulphate solutionusing carbonelectrodes.

Gas bubbles are

released at theanode and cathode.

II Combustion of 1.2gof magnesiumpowder in excessoxygen.

Glaring white flameis seen and whitepowder is formed.

(a) Based on Experiment I:(i) Draw the set up of the apparatus to carry out this experiment. In your

diagram show how the products at the anode and cathode are collected.

[3 marks](ii) State how you would verify that the gas released at the cathode is

hydrogen.

[1 mark]

(iii) Explain how hydrogen gas is produced at the cathode.

..

..

..

..

[3 marks]

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(b) Based on Experiment II:(i) The white powder formed is magnesium oxide.

Write the formula for magnesium oxide.

[1 mark]

(ii) Write the chemical equation for the reaction that takes place.

[1 mark](iii) State the oxidation number for each of the elements in magnesium oxide.

[2 marks]

4 SPM 2007/P2/Q6

Iron is a metal that rusts easily.(a) (i) State the conditions for the rusting of iron.

[1mark]

(ii) Draw a labelled diagram to show how the conditions for the rusting of ironinvolve in the ionization of iron and the flow of electron.

[3 marks](b) (i) Describe the reactions that take place at the edge of water droplet (positive

terminal) during the rusting of iron after the Fe

2+

and OH

-

ions are formed.

[3 marks]

(ii) State the change in the oxidation number of iron in 6(b)(i).

[ 1 mark]

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(c) Diagram 6 shows the use of zinc plates on an iron ship to prevent rusting.

Diagram 6(i) Explain how the zinc plates protect the iron ship from rusting.

[2 marks]

(ii) Write the half equation for the rection in 6(c)(i).

[1 mark]

5 SPM 2004/P3/Q2

Metals are arranged in the Reactivity Series based on the reactivity of metalwith oxygen.

Figure 2.1 shows the set-up of apparatus for an experiment to determine the order ofmetals in the Reactivity Series.Potassium manganate(VII) is heated to release oxygen gas to react with metal powder.

Figure 2.1The experiment is carried out using metal powders of copper, zinc, magnesium and leadreacted with oxygen respectively.

Observations on the metal powders of copper, zinc, magnesium and lead in theexperiments are shown in Figure 2.2.

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Figure 2.2

(a) Look at the flame or glow in each diagram in Figure 2.2. Complete Figure 2.2 bystating the observations for the reaction of metal powders with oxygen.

[3 marks]

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(b) Complete Table 2.3 based on the experiment.

Name of variables Action to be taken

(i) Manipulated variable:

...........

(i) The way to manipulatevariable:

..

..

...(ii) Responding variable:

.

(ii) What to observe in theresponding variable:

...

...

...(iii) Controlled variable:

.

(iii) The way to maintain thecontrolled variable:

...

Table 2.3

(c) State one hypothesis for the experiment.

..

..[3 marks]

(d) (i) Based on the observations in Figure 2.2, arrange copper, zinc, magnesium andlead in descending order of reactivity of metal towards oxygen.

Descending order of reactivity of metal towards oxygen.

[3 marks]

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(ii) The experiment is repeated by using aluminium powder to react with oxygen.The result of the experiment is shown in Figure 2.4.

Set-up of apparatus Observation on the metal

Moderately bright flame

Figure 2.4

Predict the positions of aluminium in the Reactivity Series of metals in (d)(i).Draw an arrow ( ) in (d)(i) to show the position of aluminium in this reactivityseries.

[3 marks]

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(e)

Figure 2.5

Based on the observations in Figure 2.5, classify the metals into two groups, thosewhich are more reactive than carbon and those which are less reactive than carbon.Put your answer in a suitable table.

[3 marks]

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6 SPM 2005/P3/Q2A pupil wanted to construct the electrochemical series.He measured the potential dfference of a few pairs of metals.The set up of the apparatus of his experiment is shown in Figure 2.1.

Figure 2.1

Figure 2.2 shows the results obtained from experiment after 30 minutes.

Figure 2.2

(a) Describe the change that you see in the copper(II) sulphate solution duringthe experiment.

..

..

..[3 marks]

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(b) The pupil repeated the experiment by substituting the zinc metal with iron,magnesium and lead.Each time he used copper metal as the negative electrode and freshcopper(II) sulphate solution.The following table shows the voltmeter readings he obtained from the pairsof metals.

ExperimentPairs of metal Reading of

voltmeter/ VNegativeelectrode

Positiveelectrode

I Zinc Copper 1.10II Iron Copper 0.78III Magnesium Copper 2.72IV Lead Copper 0.45

Based on the above information, complete the following table.

Manipulated variable:

..

..

..

Method to manipulate thevariable:

......

..

...Responding variable:

........................................................

....

...

How the variable is responding:

...

...

...

Controlled variable:

..

..

...

Method to maintain thecontrolled variable:

...

...

...

(c) State the hypothesis for this experiment.

..

..

..[3 marks]

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FORM 4 CHAPTER 7 ACIDS AND BASESFORM 4 CHAPTER 8 SALTS


Year 2003 2004 2005 2006 2007 2008Paper No. P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of


Question

No4 2 5 4 8 4 7 10


1. 2004/P2/STRUCTURE/Q5

Table 5 shows Experiment I and II in the preparation of salt.

(a) State one observation in Experiment I

[1 mark]

(b) Based on Experiment II:

(i) State the reason why copper(II) oxide powder is added in excess.

.......[1 mark]

(ii) State how the excess copper(II) oxide powder can be separated from theproducts.

.......[1 mark]

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(iii) State the chemical equation for the reaction that takes place in Experiment II.

.......[1 mark]

(iv) Calculate the maximum mass of the salt formed.Use the information that the relative atomic mass of O =16, S = 32 and Cu = 64.

[2 marks]

(c) Experiment I is repeated. Sulphuric acid is replaced by hydrochloric acid of the same

concentration. Predict the volume of hydrochloric acid required for a complete reaction.

.[1 mark]

(d) There are several steps in the preparation of the salts in each of the Experiments I andII. State one difference in the steps between the two experiments.

Experiment I Experiment II

[1 mark]


Table 4 shows the positive and negative ions in three salt solutions.

Name of Salt Positive ion Negative ion

Copper(II) sulphate Cu2+

SO42-

Sodium sulphate Na+ SO42-

Lead(II) sulphate Pb2+ NO3-

Table 4

Use the information in Table 4 to answer the following questions.(a) What is another name for a positively charged ion?

[1 mark]

(b) Name the ions in copper(II) sulphate solution.

ion

ion[1 mark]

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(c) Write the formula for sodium sulphate.

.[1 mark]

(d) When 10 cm3

of 0.5 mol dm-3

sodium sulphate solution is added to excess lead(II)nitrate solution, a white precipitate is formed.

(i) Write the chemical equation for the reaction.

.......[2 marks]

(ii) Describe the chemical equation in (d)(i).

.......

[1 mark]

(iii) Name the white precipitate

[1 mark]

(iv) Calculate the number of mole of sodium sulphate in the solution.Use the formula : Number of mole = Volume x Concentration

[1 mark](v) Calculate the mass of precipitate formed.

Given that the relative atomic mass of O = 16, S = 32, and Pb = 207.Use the formula : Mass = Number of mole x Relative molecular mass

[2 marks]


(a) 8 g of solid sodium hydroxide, NaOH, is dissolved in distilled water to produce a solutionof 1000 cm3.The NaOH solution produced has the concentration of 8 g dm-3 and molarity of 0.2mol dm-3.

(i) State the meaning of the concentration for the solution produced.

.[1 mark]

(Ii) State the meaning of the molarity for the solution produced.

.[1 mark]

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(iii) Write the formula that represents the relationship between the number of mole(n), molarity (M) and volume (V) for the solution.

.[1 mark]

(iv) Substitute the actual values of the number of mole, molarity and volume of theNaOH solution into the formula in 3(a)(iii).[Relative molecular mass of NaOH = 40]

[1 mark]

(b) Diagram 4.1 shows the precipitation of the standard solution of NaOH, 0.2 mol dm-3.

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(i) What are the two parameters that should be measured accurately to prepare thestandard solution of NaOH?

Parameter I :...

Parameter II :[2 marks]

(ii) After all the NaOH solution is poured into the volumetric flask, the beaker andthe filter funnel must be rinsed several times with distilled water.After each rinse, all of this water is transferred into the volumetric flask.Give one reason for doing this.

.[1 mark]

(iii) What step should be taken to ensure that the meniscus level of the standardsolution is exactly in line with the graduation mark on the volumetric flask.

.[1 mark]

(iv) A volumetric flask is more suitable to be used in the preparation of the standardsolution rather than a beaker.Why?

.[1 mark]

(v) Why is the volumetric flask stoppered after the standard solution is prepared?

.[1 mark]

4. 2003/P3/STRUCTURE/Q2A student has carried out an experiment to construct an ionic equation for the formation oflead(II) iodide. The experiment was carried out according to the following steps:

Step I 5.0 cm3 of potassium iodide solution 1.0 mol dm-3 was poured into each testtube labeled P, Q, R, S, T, U, and V.

Step II 0.5 cm3

of lead(II) nitrate solution 1.0 mol dm-3

was added into test tube P.

Step III Step II was repeated for test tubes Q, R, S, T, U, and V using the volumesin Table 1.

Step IV All the test tubes were put in the rack to allow lead(II) iodide to precipitate.

Test Tube P Q R S T U VVolume of lead(II) nitratesolution 1.0 mol dm-3/cm3

Height of lead(II) iodideprecipitate /cm

Table 1

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(a) Figure 2 shows seven test tubes for the above experiment. Using the ruler given ,measure the height of lead(II) iodide precipitate in test tubes P, Q, R, S, T, U, and V inFigure 2. Record the height of the precipitate in Table 1.

[3 marks]

(b) Based on Table 1, draw a graph of the height of the precipitate against volume of

lead(II) nitrate solution on the graph paper on page . [3 marks]

(c) On the graph that you have drawn in (b),

(i) Mark and write the minimum volume of lead(II) nitrate solution needed forcomplete reaction with 5.0 cm3 of potassium iodide solution 1.0 mol dm-3.[3 marks]

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(ii) Using the volume obtained in I(i), show the calculation for obtaining the numberof moles of Pb2+ and I- ions that are required for the formation of lead(II) iodide.Then calculate the number of moles of I- ions that has reacted with 1 mol of Pb2+

ions.[3 marks]

(iii) Write the ionic equation for the formation of lead(II) iodide.

..[3 marks]

(d) What can you observe about the height of the precipitate in Figure 2?

..

..

..[3 marks]

(e) What is your inference based on your answer in (d)?

..

..

..[3 marks]

(f) Categorise the ions found in the lead(II) nitrate solution and the potassium iodidesolution used in the experiment into positive and negative ions.

[3 marks]

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FORM 4 CHAPTER 9 MANUFACTURED SUBSTANCES IN INDUSTRY


Year 2003 2004 2005 2006 2007 2008


Type of

question


Question

No3 3 3 3 5 2 1


1. SPM 2003/P2/Q3Figure 3 shows the flow chart for the industrial manufacture of sulphuric acid and theproduction of fertilizer Z.

Based on figure 3, answer the following questions.(a) Name the process of manufacturing sulphuric acid.

[1 mark]

(b) Name the substance X.

[1 mark]

(c) Substance X could react directly with water to form sulphuric acid. Explain whythis step is not carried out in the industrial process.

[1 mark](d) Write the chemical equation when oleum reacts with water to form sulphuric

acid.

[1 mark]

(e) Name the substance Y and the fertilizer Z.

Substance Y:

Fertilizer Z : [2 marks]

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(f) Write a chemical equation when sulphur dioxide reacts with water.

[1 mark]

2. SPM 2006/P2/Q5(a) Write the chemical equation for the reaction used in Haber Process for the

industrial production of ammonia.

[ 2 marks]

(b) Graph 5 shows the percentage of ammonia production from Factory P and itscompetitor Factory Q.

(i) Based on Graph 5, compare the percentage of ammonia produced at thepressure of 200 atm from each factory.

[1 mark]

(ii) Based on your comparison in 5(b)(i), what is the effect of temperature onthe percentage of ammonia produced?

[1 mark]

(iii) One method of increasing the percentage of ammonia is by increasing thepressure. State one problem that may arise from this method.

[1 mark]

(iv) How may the problem in 5(b)(iii) be overcome?

[1 mark]

47

The combustion of petrol in the engines of vehicles produces sulphurdioxide. This gas when dissolved in rain is corrosive.


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Answer To Score Chemistry Structured Questions(c) Ammonia from the Haber Process can be used to manufacture ammonium

nitrate fertilizer, NH4NO3.(i) State one other use of ammonium nitrate.

[1 mark]

(ii) Complete the chemical equation below for the preparation of ammonium

nitrate fertilizer, NH4NO3.

.. + .. NH4NO3(s)[ 2 marks]

(iii) The apparatus below is used to make ammonium nitrate solution.Next to the arrow, draw a diagram of the set up of the apparatus used inthe preparation of ammonium nitrate crystals

[ 2 marks]

3. SPM 2007/P2/Q2Diagram 2 shows how ammonium sulphate is produced.

(a) Process X and process Y are industrial processes.What are the names of each of these processes?

X :

Y : [2 marks]

(b) What are the three raw materials needed for process X?

1.

2.

3. [3 marks]

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Answer To Score Chemistry Structured Questions(c) (i) Write a balanced chemical equation for reaction P.

[1 mark]

(ii) Use the answer in 2(c)(i) to determine the number of moles of sulphuricacid and the number of moles of ammonia used to produce 1 mole ofammonium sulphate.

Sulphuric acid:

Ammonia : [3 marks]

(d) State one use of ammonium sulphate.

[1 mark]

4. SPM 2008/P2/Q1Diagram 1 shows the manufacture of sulphuric acid.

(a) What is the name of this process?

[1 mark]

(b) State the name of catalyst X.

[1 mark]

(c) (i) State the name of substance Y.

[1 mark]

(ii) Substance Y is formed when sulphur trioxide reacts with concentratedsulphuric acid.Write the chemical equation for this reaction.

[2 marks]

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Answer To Score Chemistry Structured Questions(d) A waste gas is produced during the manufacture of sulphuric acid.

Explain briefly how this gas can cause environmental pollution.

[2 marks]

(e) The sulphuric acid produced can be used to manufacture fertilizers.(i) Name one fertilizer manufactured from sulphuric acid.

[1 mark]

(ii) State another use of sulphuric acid.

[1 mark]

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Answer To Score Chemistry Structured QuestionsCHAPTER 1 : RATE OF REACTION


Year 2003 2004 2005 2006 2007 2008

Paper

No.P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of


Question

No1 1 7

3

*6

1

05


1. SPM 2006/P2/Q6

Diagram 6 shows two experiments to investigate one factor that influence the rate of a reaction.

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Answer To Score Chemistry Structured Questions(a)

What is the factor that influences the rate of reaction in both experiment?

[1 mark]

(b)

The reaction in the experiment is represented by the following equation :

CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)

(i) Among the products stated in the equation, which is the most suitable to be chosen todetermine the rate of reaction?

..[1 mark]

(ii) State one reason for choosing the product in 6(b)(i).

..[1 mark]

(c) State two controlled variables in both experiments.

1.

2.[2 marks]

(d)

The result for both experiments are represented by Graph 6.

Graph 6

Based on Graph 6 :(i) Experiment II has a higher rate of reaction.

How does the graph show this?

..

..[1 mark]

(ii) What has happened to the reactants at timex?

..

..[1 mark]

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Answer To Score Chemistry Structured Questions(iii) Why are both curves at the same level after timex?

[1 mark]

(e

)

What is the conclusion for both experiments?

[1 mark]

(f) Another experiment is carried out using excess calcium carbonate powder and dilutehydrochloric acid with different concentrations.

Sketch the curve of concentration of dilute hydrochloric acid against the time taken to collect afixed quantity of the product.

[2 marks]

53

Concentration of dilutehydrochloric acid

Time taken to collect a fixedquantity of product


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2. SPM 2008/P2/Q5An experiment is carried out to investigate the rate of reaction of zinc with hydrochloric acid. Excesszinc powder is added to 20 cm3 of 0.2 mol dm-3 hydrochloric acid. The volume of gas collected atregular intervals is shown in Diagram 5.1.

Diagram 5.1

(a)

State the meaning of the rate of reaction.

...........[1 mark]

(b)

From the graph in Diagram 5.1, determine :

(i) The rate of reaction at 120 s.

[2 marks]

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(ii) The average rate of reaction between 60 s and 120 s.

[1 mark]

(c) Explain why the rate of reaction decreases with time.

...........[1 mark]

(d)

Another experiment is carried out to study the factors that affect the rate of the reaction. Theresult of this experiment is shown in Diagram 5.2. Curve I represents the result of thisexperiment using excess zinc powder and 50 cm3 of 1.0 mol dm-3 dilute hydrochloric acid.

Diagram 5.2

(i) Suggest the factors that influence the rate of reaction to obtain the curves labeled II andIII.

Curve II : ..

Curve III : ............[2 marks]

(ii) Describe briefly how to carry out the experiment to obtain the curve labeled III.

[3 marks]

(iii) Give one reason why the final volume of gas obtained in curve III is half the final volume ofgas in curve I.

...

...[1 mark]

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3. SPM 2003/P3/Q1An experiment was conducted to find out the effects of temperature on the rate of reaction. 50 cm3 ofsodium thiosulphate solution 0.05 mol dm-3 at 30 oC was put in into 250 cm3 conical flask. Then theconical flask was placed on an X sign on a piece of white paper.

10 cm3

of hydrochloric acid 1.0 mol dm-3

was added to the sodium thiosulphate solution and shaken.At the same time, the stop watch was started. The stop watch was stopped as soon as the X signwas no longer visible.

The same steps of the experiment were repeated for sodium thiosulphate solution which was heatedto 35 oC, 40 oC, 45 oC and 50 oC.

Figure 1 shows the readings of the stop watch for each of the reactions at different temperatures.

(a)

Record the time for each reaction in the spaces provided in Figure 1.[3 marks]

(b

)

Construct a table and record temperature, time and 1/time for this experiment.

[3 marks]

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(c) (i) Draw a graph of temperature against 1/time on the graph paper.

(ii) Based on the graph in (c) (i), state the relationship between the rate of reaction andtemperature.

.

.[3 marks]

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Answer To Score Chemistry Structured Questions(d)

Predict the time taken as soon as the sign X to be no longer visible if this experiment isrepeated at 55o C.

[3 marks]

(e)

(i) State the variable involved in this experiment.Manipulated :

Responding variable :

Constant variable :

[3 marks]

(ii) State how you would manipulate one variable while keeping the other variables constant.

[3 marks]

(f) State the hypothesis for this experiment.

.

.[3 marks]

(g)

From the above experiment, the student found a relationship between temperature and rate ofreaction. The same situation can be applied in our daily lives, for example, keeping food that iseasily spoiled in the refrigerator.

Using your knowledge of chemistry, state the relationship between temperature and the rate atwhich food turns bad.

.

.[3 marks]

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FORM 5 CHAPTER 2 CARBON COMPOUNDS

ANALYSIS OF PAST YEAR QUESTIONS FROM 2003 - 2008

Year 2003 2004 2005 2006 2007 2008


Type ofquestion


Question No 4 6 2 3 9 4 1


1 SPM 2003/P2/Q4Figure 4 shows the set-up of apparatus for the preparation of ethyl ethanoate from thereaction of ethanol with ethanoic acid.

(a) On the Liebig condenser in Figure 4, mark X to indicate the place where water flowsin and Y where water flows out.

[1 mark]

(b) Why is the mixture heated using a water bath?

[2 marks]

(i) Name the reaction for the preparation of ethyl ethanoate.

.[1 mark]

(ii) Write the chemical equation for the reaction in (c)(i).

.[1 mark]

(c) The experiment is repeated by replacing ethanol with propanol.

(i) Name the ester formed.

[1 mark]

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Answer To Score Chemistry Structured Questions(ii) State one physical property of the ester.

[1 mark]

(d) The flow chart below shows the conversion of ethanol to ethane and ethanol toethanoic acid.

Based on the flow chart, write the chemical equation for

(e) (i) Process I.

..[1 mark]

(ii) Process II

[1 mark](f) An alkene has a structural formula as shown below

What is the name of the alkane?

.[1 mark]

2 SPM 2004/P2/Q6Figure 6 shows the reaction in the preparation of margarine.

(a) (i) Name the process used to produce margarine in Figure 6.

[1 mark]

(ii) State one effect of this process on the vegetable oil.

..[1 mark]

(b) (i) Name catalyst X and state the range of temperature Y in the production ofmargarine.

Catalyst X:

Temperature Y: ........

o

C. [2 marks]

[Concept based on Chapter 1: Rate of reaction]

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Answer To Score Chemistry Structured Questions(ii) Based on the collision theory, explain the effect of catalyst X and temperature Y

in the production of margarine.

.[3 marks](iii) Write the chemical formula for margarine in Figure 6.

[1 mark]

(c) Name one example of a vegetable oil used in the production of margarine.

..[1 mark]

3 SPM 2008/P2/Q4The following information is about the compound C2H5OH.

(a) What is the name of this compound?

[1 mark]

(b) What is the general formula for the homologous series of this compound?

..[1 mark]

(c) One mole of this compound undergoes complete combustion to form gas X and wateras shown below.

(i) State the name of gas X

[1 mark]

(ii) What are the values of m and n?

m = ..

n = .

[2marks]

61

Miscible in all proportions with water

Undergoes combustion

A member of a homologous series

C2H5OH + mO2 nX + 3H2O


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Answer To Score Chemistry Structured Questions(d) Compound C2H5OH reacts with ethanoic acid to produce compound Y which has a

sweet pleasant smell.(i) State the name of compound Y.

[1 mark]

(ii) Draw the structural formula of compound Y.

[1 mark]

(e) Compound C2H5OH undergoes dehydration to produce ethene.(i) Suggest one dehydration agent for this reaction.

...[1 mark]

(ii) Draw an apparatus set-up for this dehydration reaction to collect ethane.

[2 marks]

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4 SPM 2008/P3/Q1Diagram 1 shows three sets, Set I, Set II and Set III, of the apparatus set-up for anexperiment to investigate the effect of ethanoic acid and ammonia solution on thecoagulation of latex.

(a) State one hypothesis based on Set I and Set II.

..[3 marks]

(b) Record the time taken for the latex to coagulate in Set I and Set III.

Set I : ..

Set III: ..[3 marks]

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(c) Construct a table to record the time taken for coagulation in Set I and Set III.

[3 marks](d) State one observation that can be obtained from each set of this experiment.

Set I: .

Set II: .

Set III: .[3 marks]

(e) State the operational definition for the coagulation of latex.

..

..

[3 marks]

(f) For this experiment, state:

(i) The manipulated variable

(ii) The responding variable

(iii) The constant variable

.[3 marks]

(g) (i) Excess hydrochloric acid is added to the beaker in Set II after 2:00 p.m. Whatobservation can be made about the latex?

.

.[3 marks]

(ii) Explain the answer in 1(g)(i)

..

..

.[3 marks]

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(h) Explain why latex can coagulate without acid in Set III.

.

..

.[3 marks](i) (i) [Concept: F5 Chapter 1: Rate of reaction]

Explain why the latex in Set I coagulates faster than the latex in Set III.

..

..[3 marks]

(ii) The following is a list of chemical substances: Nitric acid Sodium hydroxide Methanoic acid Potassium hydroxide

Classify these substances into substances that can coagulate latex andsubstances that cannot coagulate latex.

[3 marks]

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CHAPTER 4 : THERMOCHEMISTRY


Year 2003 2004 2005 2006 2007 2008


Type ofquestion S E S E S E S E S E S E S E S E S E S E S E S E

Question

No6 4

3

51 1 6

1. SPM 2003/P2/Q6

A student carried out an experiment to determine the heat of displacement for the reaction

between copper and silver nitrate solution. In this experiment, excess copper powder was added

to 100 cm3 of silver nitrate solution 0.5 mol dm-3. The heat of displacement in this experiment was

-105 kJ mol-1.

[Specific heat capacity of the solution is 4.2 Jg-1 C-1, and the density of the solution is 1 g cm-3]

(a)

What is meant by heat of displacement ?

.

[1 mark](b)

Besides the data given above, state one other piece of data that is needed to calculate theheat of displacement.

.[1 mark]

(c) State one precaution that must be taken while carrying out the experiment.

.

[1 mark](d)

(i) State one observation of the experiment.

..

[1 mark](ii) State the reason for the observation in (d) (i)

..

[1 mark]

(e)

Based on the information from this experiment, calculate

(i) the number of moles of silver ions reacted.

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[1 mark]

(ii) the amount of heat released.

[1 mark]

(iii) the change in temperature.

[1 mark]

(f) Draw an energy level diagram for the reaction in this experiment.

[2 marks]

(g)

The experiment is repeated using 100 cm3 of 1.0 mol dm-3 silver nitrate solution and excesscopper powder. Calculate the temperature change in this experiment. Explain why thischange of temperature is different from that in (e) (iii).

[3 marks]

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2. SPM 2004/P2/Q4

Figure 4 show the set-up of the apparatus of an experiment to determine the heat ofprecipitation. 25.0 cm3 of 0.5 mol dm-3 silver nitrate solution is reacted with 25 cm3 of 0.5 mol dm-3

sodium chloride solution. As a result there is a change in temperature of the mixture and a whiteprecipitate is formed.

Beforereaction

Afterreaction

Figure 4

(b)

Why is a polystyrene cup used in the experiment ?

[1 mark]

(i) Based on the change of temperature in the experiment, state the type of reaction thatoccurred.

.[1 mark]

(ii) How is the total energy of the product different from the total energy of the reactants?

.[1 mark]

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Answer To Score Chemistry Structured Questions(c) State one step that should be taken while adding the two solutions in order to get a more

accurate result.

[1 mark]

(d)

The ionic equation for the precipitation reaction of silver chloride is :

Ag+

(aq) + Cl-

(aq) AgCl(s)

(i) What is the number of moles of Ag+ ions that reacted with Cl- ions ?

[1 mark]

(ii) Calculate the heat change of the precipitation reaction that has taken place. Use theinformation that the specific heat capacity of water is 4.2 J g -1C-1 and density water is1 g cm-3.

[2 marks]

(iii) Calculate the heat of precipitation for this reaction.

[2 marks](e)

The calculated value of the heat of precipitation for this reaction is less than the actualvalue.Give a reason.

[1 mark]

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Answer To Score Chemistry Structured Questions3. SPM 2005/P2/Q3

A pupil carried out an experiment to determine the value of heat of displacement. Figure 3 showsthe set up of the apparatus used in the experiment.

Figure 3

The following data was obtained :

(a)

Complete the ionic equation for the reaction that occurred.

Zn + Cu2+

. [1 mark](b)

In this experiment, excess zinc is added to 100 cm3 of 0.5 mol dm-3 copper(II) sulphatesolution.Given that the specific heat capacity of the solution is 4.2 J g-1 oC-1 and the density of thesolution is 1.0 g cm-3.

(i) Calculate the change of heat capacity of the experiment.Use the formula, H = mc

[2 marks](ii) Calculate the heat of displacement in the experiment.

The number of moles of copper(II)sulphate that reacted = ......

Heat of displacement = ...[2 marks]

70

Glass cup

Copper (II) sulphateSolution

Zinc Powder

Initial temperature of copper(II) sulphate solution, 1 = 28 oCHighest temperature of the mixture of product, 2 = 48 oC


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Answer To Score Chemistry Structured Questions(c) Draw the energy level diagram for the reaction.

[2 marks](d)

It was found that the heat of displacement value in (b)(ii) is not the same as the actual value.Suggest one step that must be taken to get a more accurate value.

[1 mark]

(e)

Based on the experiment, what is meant by the heat of displacement?

[1 mark]

(f) The pupil repeats the experiment, replacing the metal zinc with metal X.The following equation shows the reaction and the value of heat of displacement of metaliron and metal X.

Equation I :Fe (s) + CuSO4 (aq) FeSO4 (aq) + Cu(s), H = -150 kJ mol-1

Equation II :X(s) + CuSO4 (aq) XSO4 (aq) + Cu(s), H = - 100 kJ mol-1

Predict the metal X.Choose from this list : Aluminium, magnesium and tin.

[1 mark]

4. SPM 2005/P2/Q5

(a)

What is the meaning of the heat of combustion of an alcohol?

[1 mark]

(b)

Table 5 shows the heat of combustion of three types of alcohol.The number of carbon atoms and the attractive force between molecules are among thefactors that affect the value of heat of combustion.

Name of alcohol Molecular formula Heat of combustion /kJmol-1

Methanol CH3OH 725Ethanol C2H5OH 1376Propanol C3H7OH 2015

Table 5

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Answer To Score Chemistry Structured Questions(i) Use data from Table 5 to draw the graph of the heat of combustion against number of

carbon atoms on the graph paper provided.[2 marks]

(ii) Based on the graph in (b)(i), as the number of carbon atoms increases so does thevalue of the heat of combustion.

Explain why.

[2 marks]

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Answer To Score Chemistry Structured Questions(iii) Calculate the heat released when 2.3g of ethanol is completely burnt in air.

Given that the relative atomic mass of C=12, H=1, O=16.Use the formula :Heat released = Number of moles X Heat of combustion.

[2 marks](c) Methanol and ethanol do not have isomers.

Propanol has two isomers.Draw the structures of the two isomers of propanol.

[2 marks](d)

Table 5.2 shows the freezing and the boiling points of mercury, methanol, ethanoland butanol.

Substance Freezing point /0C Boiling point /0C

Mercury -39 357Methanol -97 64Ethanol -117 79Butanol -90 117

Table 5.2A thermometer may contain mercury or an alcohol.A mercury thermometer is not suitable to measure the temperature at around -100 0C.Name a suitable alcohol that can be used in a thermometer to measure the temperature ataround 100 0C.Give one reason for your choice.

Name of alcohol : ....

Reason : ....

....

....[2 marks]

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Answer To Score Chemistry Structured Questions5. SPM 2006/P3/Q1

Diagram 1.1 shows two experiments to determine the heat of neutralisation.

Experiment I

Reaction between 25 cm3 of sodium hydroxide solution, NaOH, 2.0 mol dm-3 and 25 cm3 of

ethanoic acid, CH3COOH, 2.0 mol dm-3

.

Initial temperature of mixture : C

Highest temperature of mixture : C

Change in temperature : C

Experiment II

Reaction between 25 cm3

of sodium hydroxide solution, NaOH, 2.0 mol dm-3

and 25 cm3

ofhydrochloric acid, HCl, 2.0 mol dm-3.

Initial temperature of mixture : T1 C

Highest temperature of mixture : T2 C

Change in temperature : T3 C

Diagram 1.1

(a)

Write the initial and the highest temperature of the mixture and change in temperature forExperiment I in Diagram 1.1.

[3 marks]

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Answer To Score Chemistry Structured Questions(b)

Construct a table that can be used to record the data from both experiments.

[3 marks](c) State one hypothesis for both experiments.

[3 marks]

(d

)

Based on the temperature in Experiment I, predict the predict the change in temperature in

Experiment II.

[3 marks]

(e)

Why must the initial temperature and the highest temperature be recorded in theseexperiments?

[3 marks]

(f) How can the value of the changes in temperature be obtained?

[3 marks]

(g)

State three observations that you could obtain in Experiment I other than the change intemperature.

1

2

3[3 marks]

(h)

State three constant variables in this experiment.

1

2

3[3 marks]

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(i) Diagram 1.2 shows the calculation to determine the heat of neutralization for the reaction inExperiment I and Experiment II.

Experiment I

Heat release

= mc= 50 g x 4.2 4.2 J g-1 oC-1x oC= xJ

Heat of neutralization

= xkJ_________________________________

Number of mole of water produced

Experiment II

Heat release

= mc= 50 g x 4.2 4.2 J g-1 oC-1x T3 oC= yJ

Heat of neutralization

= y kJ_________________________________

Number of mole of water produced

Diagram 1.2

Based on Diagram 1.2 :(i) Give the operational definition for the heat of neutralization.

.

.[3 marks]

(ii) It was found that the value ofyis greater than the value ofx.

Explain why..

.[3 marks]

(j) The experiment is repeated using the methanoic acid.The values of the heat of neutralization of these acids are given in Table 1.Complete Table 1 by classifying the acids as strong acid or weak acid.

Name of acid Heat of neutralization/kJ mol-1 Type of acid

Ethanoic acid -50.3

Hydrochloric acid -57.2

Mathanoic acid -50.5

Table 1

[3 marks]

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6. SPM 2007/P3/Q1

Diagram 1.1 shows the apparatus set-up for experiments I, II, III and IV.The magnification of the thermometers shows the readings of the initial temperature and thehighest or lowest temperatures in each experiment.

(a) (i) Record the temperature readings in the spaces provided in Diagram 1.1. [3 marks]

Experiment I

Experiment II

Experiment III

Experiment IV

Diagram 1.1

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(ii) Construct a table to show all the data in each of these experiments.

[3 marks](iii) Classify the reactions in these experiments as either exothermic reactions or

endothermic reactions.

Exothermic reaction Endothermic reaction

[3 marks](b)

A student repeated Experiment I several times.

(i) State three things must be kept constant in these experiments.

1

2

3[3 marks]

(ii) State the hypothesis for Experiment I.

.

.

[3 marks](c) Based on Experiment II :

(i) Sate the temperature change and give two reasons for the change.

Temperature change :

.

Reason1 :

.

Reason2 :

.

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Answer To Score Chemistry Structured Questions[3 marks]

(ii) Sate the operational definition for the reaction that takes place.

.

.

[3 marks](d)

The reaction in Experiment III is a neutralization reaction.Other acids can be substituted for hydrochloric acid.These acids have the same volume and concentration as the hydrochloric acid inExperiment III.Predict the temperature in the neutralization reactions of these acids.

1. Sulphuric acid : .. oC

2. Nitric acid : .. oC

3. Ethanoic acid : .. oC

[3 marks]

(e)

Diagram 1.2 shows some observations in experiment IV.

Diagram 1.2

(i) State three observations shown in Diagram 1.2.

1

2

3[3 marks]

(ii) The following chemical equation represents the reaction in Experiment IV.

HCl(aq) + NaHCO3(aq) NaCl(aq) + CO2(g) + H2O(l)

Based on the chemical equation, and the answer in 1(e)(i), what inference can bemade from Experiment IV?

.

.[3 marks]

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(iii) Sketch a graph to show the change in the volume of carbon dioxide gas producedagainst time.

[3 marks]

7. SPM 2008/P2/Q6

The thermochemical equation for the neutralization reaction between nitric acid and sodiumhydroxide solution is given below.

(a)

State the meaning of heat of neutralisation.

[1 mark]

(b)

Based on the given thermochemical equation, state one observation when dilute nitric acidis added to sodium hydroxide solution.Explain your answer.

[2 marks]

(c) In an experiment, 100 cm3 of 2 mol dm-3 nitric acid solution was added to 100 cm3 of 2 moldm-3 sodium hydroxide solution.[Specific heat capacity of solution = 4.2 J g-1 oC-1;Density of solution = 1 g cm-3]

Calculate(i) The heat energy released in this experiment,

80

HNO3 + NaOH NaNO3 + H2O , H = -57.3 kJ mol-1


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[2 marks](ii) The temperature change in this experiment.

[2 marks](d)

Draw the energy level diagram for the reaction between nitric acid and sodium hydroxide.

[2 marks](e)

Nitric acid and ethanoic acid both react with sodium hydroxide by a neutralisation reaction.

HNO3 + NaOH NaNO3 + H2O , H = -57.3 kJ mol-1

CH3COOH + NaOH CH3COONa + H2O , H = -55.2 kJ mol-1

Explain why the heat of neutralisation for each reaction is slightly different.

..

[2 marks]

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FORM 5 CHAPTER 5 CHEMICALS FOR CONSUMERS


Year 2003 2004 2005 2006 2007 2008


Type of


Question No 2 2 2 1 1 7

5. SPM 2004/P2/Q2(a) In preparing soap, a strong alkali solution is added to fats. The mixture is heated

and then sodium chloride is added.(i) Name one strong alkali used in preparing soap.

[1 mark]

(ii) Why is sodium chloride added to the mixture?

[1 mark]

(b) The statement below is about soap and a detergent.

You have two socks stained with oil.Describe briefly, the experimental procedure, observations and conclusions toprove the above statement, by using substances such as soap, detergent and hardwater.

Procedure of the experiment:

..

..

..

..[3 marks]

Observations:

..

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The cleaning action of a detergent is moreeffective than a soap in hard water.


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Answer To Score Chemistry Structured Questions[1 mark]

Conclusions:

..

.[1 mark]

(c) Analgesic and psychotherapeutic medicines are used to treat patients. Aspirin isan analgesic medicine and barbiturate is a psychotherapeutic medicine.(i) What is the function of a barbiturate?

..[1 mark]

(ii) Children are advised not to take aspirin because it bleeding of the intestineand stomach.

Suggest one after other medicine to replace the aspirin.

..[1 mark]

(iii) Figure 2 shows the structural formula of aspirin.

Figure 2

What is the molecule formula of aspirin?

..[1 mark]

(iv) What is the molecular mass of aspirin?Use the information that the relative atomic mass of H = 1, C = 12 and O =16.

[1 mark]

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6. SPM 2005/P2/Q2The following equation shows a reaction in the preparation of soap in a laboratory. boilPalm oil + concentrated sodium hydroxide sodium palmitate (soap) + Glycerol

(a) What is the name of this reaction?

[1 mark]

(b) (i)[F5 Chapter 2 Carbon compounds]

What is the homologous series of palm oil?

..[1 mark]

(ii) Complete the anion part of the soap particle in the space provided.

[1 mark]

(c)

[F4 Chapter 8 Salts]

A pupil want to prepare a potassium palmitate soap.What alkali should he use?

[1 mark]

(d) Figure 2.1 shows part of the washing action of detergent particles on a greasestained cloth.

Figure 2.1

(i) State the part of a detergent particle that is soluble in grease.

.[1 mark]

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(ii) Based on Figure 2.1 explain the washing action of detergent particles ongreasy stains.

.

.

.

[3 marks]

(iii) Complete Figure 2.2 to show the condition of grease and detergent particleswhen the water is stirred.

Figure 2.2

[1 mark]

7. SPM 2006/P2/Q1(a) Diagram 1.1 shows a ginger plant.Ginger can be used as a traditional medicine.

Diagram 1.1

(i) Which of the parts P, Q, R or S, is used as the main source of medicine?Mark () for your answer in the box provided in Diagram 1.1

[1mark](ii) What illness can be cured by using ginger?

..[1 mark]

(iii) How is ginger used to treat the illness in 3(a)(ii)?

..

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Answer To Score Chemistry Structured Questions[1 mark]

(b) Table 1.1 shows the functions of three types of medicine.

Table 1.1

(i) Complete Table 1.1 to show which medicines have the functions given in thetable.[3 marks]

(ii) What is the side effect of medicine of type X if it is used by a child of lessthan 2 years old?

.[1 mark]

(iii) A patient treated by medicine of type Y must complete all the supply given bythe doctor in order to make sure all the bacteria are killed.

What will happen if not all the bacteria are killed?

..[1 mark]

(iv) Tranquilizer is an example of medicine of type Z.Give one change that might happen to a patients emotions when treatedusing this medicine.

.[1 mark]

8. SPM 2007/P2/Q1The following equation shows how soap can be prepared.

(a) (i) What is the name of this process?

[1 mark]

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Palm oil + sodium hydroxide Substance X + Soap

Function Type of medicine

Prevents pain

Kills or prevents the reproduction of bacteria

Changes the emotions and behavior of thepatient

X:

Y:

Z:.


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(ii) State the name of substance X.

...[1 mark]

(iii) Sodium chloride solid is added to the soap mixture to complete this process.Explain why.

..[1 mark]

(b) Two cleaning agents, J and K, are used to wash clothes in sea water and riverwater. Table 1 shows the result obtained.

(i) State the type of cleaning agents J and K.

J :

K: [2 marks]

(ii) What is the meaning of scum?

.[1 mark]

(iii) What are the two ions in sea water that cause the formation of scum?

1. .

Cleaning agent Sea water River water

J Forms scum Does not form scum

K Does not form scum Does not form scum

b structured questions

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