chemistry p2 perfect score phase ii

Perfect Score SeminarCHEMISTRY

(2nd Phase)

by

Mr. Lim Yeok Lee

SC & MATH Department

SMK St. Francis, Melaka

Motivasi 1 Motivasi 2

Format Soalan Laporan LPMKertas

2

Format: Apparatus:……………………..

Materials:……………………….

Labeled diagram: (Only compulsory if stated in the question)

Procedure:

1.

2.

:

Observation:…………………….

Conclusion: …………………….

Chemical equation: If there is any

(VI) Experiment-based questionsEssay paper 2: Section C (10 – 12 %)Essay paper 2: Section C (10 – 12 %)

Describe a laboratory experiment……Describe a laboratory experiment……

Example: Q10 SPM 2013 No. 10 (c)

Describe a laboratory experimentDescribe a laboratory experiment

(c) Preparation of magnesium sulphate salt in the laboratory

Apparatus and materials: Measuring cylinder, beaker, filter funnel, filter

paper, sulphuric acid, magnesium nitrate and potassium carbonate. √1

Procedure:1. Pour 25 cm3, 1.0 mol dm-3 of potassium

carbonate solution into a beaker. √12. Add 25 cm3, 1.0 mol dm-3 of magnesium nitrate

solution into the same beaker. √13. Filter and rinse the mixture. √1 4. Measure 25 cm3, 1.0 mol dm-3 of sulphuric acid

into another beaker.

5. Add the residue, magnesium carbonate until excess into the sulphuric acid. √1

6. Filter the mixture. √1 7. Heat the filtrate, magnesium sulphate solution

until saturated. √1 8. Cool the substance formed and filter. √1 Chemical equation: √1 K2CO3 + Mg(NO3)2 MgCO3 + 2KNO3 √1 √1 MgCO3 + H2SO4 MgSO4 + CO2 + H2O √1

(max = 10 %){**Range of volume = 20 - 100 cm3 and concentration:0.1 - 2.0 mol

dm-3)

6

1. Leaving out the key action words / phrase: Add something (zinc powder) to something else

(hydrochloric acid)Stir evenlyMix together more than two substancesHeat gently / warmHeat strongly

(VI) Mistakes in experiment-based questions

7

2. Not stating the quantities used •For solutions a certain volume (based on apparatus used) and molarity(0.1 – 2.0 mol dm-3) should be mentioned.

•For change in temperature, a certain range / increase / decrease in temperature should be mentioned.

•For solids a certain mass should be mentioned, or whether it should be used in excess.

3. Describing an observation e.g. Hydrogen gas is released (X = 0%)

Correct : Bubbles of colourless gas released or effervescence4. Drawing graphs: The axes not labeled and / or units not mention, size too small. (**line or curve must at least half or more than size of graph paper)

Both valuesBoth valuesmust write.must write.

Sharp edge Sharp edge (use ruler) (use ruler)

curve line curve line (free hand) (free hand)

Time / minTime / min

Label with Label with unit unit

√1 label with unit√1 uniform scale√1 all point mark correctly with ‘x’√1 smooth line or curve.

Temperature /Temperature /00CC

Wrong scaleWrong scale

Size less thanSize less thanhalf of graphhalf of graphPaper given.Paper given.

Maximum Maximum mark =mark =1%1%if the label if the label of X and Y of X and Y

axis areaxis arecorrect.correct.

11

5. Confused the meaning / concept of Electrochemical Series with Reactivity Series

e.g. Zinc can displace copper from copper (II) sulphate solution because zinc is higher than copper in the Reactivity Series. (X)

(should be Electrochemical Series)

c. Electrochemical series K+

Na+

Ca2+

Mg2+

Al3+

Zn2+

Fe2+

Sn2+

Pb2+

H+

Cu2+

Hg2+

Ag+

Au2+

Acid / Hydrogen

ion

King

Narnia

can

make

aluminium

zebra

fly.Superman’s

pet

has

copper

house

atAustralia

Active metals whichcan react with acid

to produce hydrogen

d. Reactivity series KNaCaMgAlCZn H2

FeSnPbCuHgAg

Au

H2

(Hydrogen gas)

Carbon

14

6. Not stating the state / size of substance e.g. Not stating aqueous potassium iodide or potassium iodide solution Not stating magnesium powder where

size of reactant matters

15

7(a) Not knowing the meaning of compare and contrast (differentiate)Compare: Find the similarities (if there is any) and differences between 2 or more thingsContrast : Find only the differences between 2 things.

16

7(b) e.g. Not knowing the meaning of compare and contrast:Question: Compare the properties of ionic and covalent compound

Students Answer: Ionic compounds have high boiling point and melting point, can dissolve in water and conduct electricity in molten or aqueous form. (X = 0%)(Properties of covalent compound not stated)

17

Correct aCorrect answer:nswer:

Ionic compounds have high boiling point and melting point, can dissolve in water and conduct electricity in molten or aqueous form. While covalent compounds have low boiling point and melting point, insoluble in water and not be able to conduct electricity in any state.

Specific comparison

Example:

Question:

Compare the physical properties of tetrachloromethane and magnesium oxide.

(6 marks)

Answer:

Tetrachloromethane Magnesium oxide

(i) It has low melting and

boiling point. √ 1

It has high melting and boiling point. √ 1

(ii) It cannot conduct

electricity in all states.

√ 1

It can only conduct electricity in molten state.

√ 1

(iii) It is soluble in

organic solvent. √ 1

It is insoluble in organic solvent. √ 1

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1. (for explanation on formation of ionic bond) Sodium donates electron. (X = 0%)

Correct : One sodium atom donates one electron

2. Stable electron arrangement (X = 0%)Correct: Stable octet electrons arrangement

3. Rate of reaction described as fast or slow eg. The higher the temperature the faster the rate of reaction. (X = 0%)

Correct: The higher the temperature the higher the rate of reaction.

IncompleteIncomplete // Inaccurate statementInaccurate statement // phrasesphrases

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4. Rate of reaction getting slower. (X = 0%) Correct : Rate of reaction getting lower .√ (Rate of reaction decreases ). √

5.The smaller the size of substance the bigger the surface area. X

Correct : The smaller the size of the substance the

bigger is the total surface area.


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6. An ionic compound can conduct electricity (X = 0%) Correct: An ionic compound can conduct electricity in the molten state or in aqueous solution. √


23

7. Definition on “Relative atomic mass” i. Based on hydrogen concept Relative atomic mass of an element is the number of times the

mass of one atom of an element is heavier than the mass of hydrogen. X

Correct : Relative atomic mass of an element is the number of times an atom of an element is heavier than the mass of one atom of hydrogen. √

(or) Based on carbon concept Relative atomic mass of an element is the number of times the mass

of one atom of an element is heavier than 1/12 of the mass of a carbon-12 atom. √

Incomplete/Inaccurate statementIncomplete/Inaccurate statement /phrases/phrases

24

8. A hydrocarbon is organic compound that contains the elements of carbon and hydrogen. (x)

Correct : A hydrocarbon is organic compound that contains the elements of carbon and hydrogen only. (√)


25

9. An alkali is a substance that contains hydroxide ions. (x)

Correct : An alkali is a substance that produces hydroxide ions when dissolved / ionises in water. (√)


26

10. An acid is a substance that contains hydrogen ions. (x)

Correct : An acid is a substance that produces hydrogen ions when dissolved / ionises in water. (√)


27

11. Calcium is situated in Period IV. (x)

Correct : Calcium is situated in Period 4. (√)


28

12. A chloride ion has three electron shells. (x)

Correct : A chloride ion has three shells filled with electrons. (√)

(or)

A chloride ion has three occupied electron shells.

(√)


29

13. Example: Reaction between zinc and hydrochloric acid.

When the temperature is increased, the number of collisions also increases. (x)

Correct : When the temperature is increased, the number of collisions between [the named particles] also increases. (√)


30

Correct : When the temperature of hydrochloric

acid increased, the number of collisions between zinc atoms and hydrogen ions also increases. (√)

31

14. Example: Fe2+ Fe 3+ + e The oxidation number of Fe 2+ ion changes / increases. (x) Correct : The oxidation number of iron in

Fe 2+ ion increase from +2 to +3. (√)


32

15. A polystyrene cup is used to prevent heat loss. (x)

Correct : A polystyrene cup is used to reduce

heat loss. (√)


16. Attractive forces between molecules are

small / lower / higher. (x)

Correct: Attractive forces between

molecules (Intermolecular forces) are

weak / strong. (√)

04/18/23 Program Intervensi PPSMI 2007 33

17. Copper attracted to the cathode. (x)

Correct: Copper ions attracted to to

the cathode. (√)

18. The ions in the electrolyte can move. (x) Correct :The ions in the electrolyte

can move freely. (√)

04/18/23 Program Intervensi PPSMI 2007 34

ENERGY LEVEL DIAGRAM

• Vertical axis must be labeled as energy• Draw two horizontal lines at different level• The name / formula of the reactants and the name /

formula of the products must be written at the correct level

• Label the ΔH • Example: Draw the energy level diagram for

neutralisation process between sodium hydroxide and hydrochloric acid

ENERGY LEVEL DIAGRAM Energy

NaOH + HCl

NaCl + H2O

H= -57.3kJmol-1

Solid

Drawing DiagramsDrawing Diagrams

Minimum 3 x 3Minimum 3 x 3

(x = 0%)

(x = 0%)

(x = 0%)

(x = 0%)

(x = 0%)

Liquid


Gas


mixture of solid and liquid


Draw the arrangement of atom in brass (loyang)

Copper atom

Zinc atom

42

Good Luck!Good Luck! A+A+

chemistry p2 perfect score phase ii

Documents

cprogram intervensi

magnesium sulphate solution

magnesium carbonate

magnesium nitrate solution

magnesium powder

potassium carbonate

potassium iodide solution

filter paper