chemistry revision presentation on section b dan c past year paper = ogos 2011
DESCRIPTION
Basic chemistry revisionTRANSCRIPT
Year 2007 No 7c)
REVISON ON SALT
(c) Table 7 shows the observations from some tests carried out on salt X.
Test Observation
I: Heating of salt X solid
A metal oxide is formed and a brown gas is given off
II. Salt X solution is mixed with excess aqueous ammonia
A white precipitate which is insoluble in excess aqueous ammonia is formed
Based on the information in Table 7: (i) Identify an anion that is present in Test I and describe a chemical test toverify the anion [4m]
• Anion is nitrate ion
Based on the information in Table 7: (i) Identify an anion that is present in Test I and describe a chemical test toverify the anion [4m]
Chemical test:• Pour 2 cm3 of the solution X into a test tube • Add dilute sulphuric acid followed with iron(II) sulphate solution• Shake well the mixture and slant the
test tube• Add concentrated sulphuric acid slowly
drop by drop. Observation: brown ring formed
(ii) Identify three cations that are present in Test II and describe a chemical test to verify the cations. [6m] • Cations present: Mg2+, Pb2+, Al3+
Test with NaOH:- Add little NaOH solution then in excess-Observation: • If white precipitate soluble is formed, then Pb2+ and Al3+ present• If white precipitate is formed ,then Mg2+ is present
Confirmatory test using Na2SO4 :• Pour 2 cm3 of solution X into a test
tube• Add sodium sulphate solution to
the solution X• If no precipitate is formed , then
Al3+ present
• If white precipitate formed, then Pb2+ present
OR
Confirmatory test using KI solution :• Add potassium iodide solution to
the solution, shake well • If no precipitate formed, then Al3+
present• If yellow precipitate formed, then
Pb2+ present
REVISION ON CARBON COMPOUND
SPM 2007 NO : 9a
Diagram 9 shows how compound G is formed from alkene
Alkene + H2O
Compound F
Compound G + H2O
Phosphoric acid, 300OC, 60 atm
Porcelain chips
(i) Name one alkene that has less than four carbon atoms. Draw its structural formula.
ethene propeneor
ii) Based on your answer in 9 ai) what is the name of compound F and Compound G
Name of alkene
ethene propene
Name of Compound F
ethanol propanol
Name of Compound G
ethene propene
Alkene + H2O
Compound F
Compound G + H2O
Phosphoric acid, 300OC, 60 atm
Porcelain chips
iii) State three chemical properties of compound F and three properties of compound G
• COMPOUND F ( alcohol)
1. Burn in excess oxygen producing water and carbon dioxide.
2. Can be dehydrated to produce alkene.3. Can be oxidised to produce carboxylic acid
Alkene + H2O
Compound F
Compound G + H2O
Phosphoric acid, 300OC, 60 atm
Porcelain chips
• COMPOUND G (alkene)1. Burns in excess oxygen to form CO2 and H2O.
2. Undergoes additional reaction:1. Hydrogenation to produce alkane2. Hydration to produce alcohol3. Halogenation
3. Undergoes polymerisation reaction .
Alkene + H2O
Compound F
Compound G + H2O
Phosphoric acid, 300OC, 60 atm
Porcelain chips
REVISION ON CARBON
COMPOUNDS
SPM 2007, Q: 9b
Alkenes, alcohols and carboxylic acids are three different homologous series. Construct a table to show the general formula , the functional group and the name of a member in each of the series.
HMLGOS SERIES
ALKENE ALCOHOLS CARBOXYLIC ACIDS
GEN FORMLA
CnH2n
n= 2,3, 4…
CnH2n+1OH n= 1,2, 3….
CnH2n+1COOH
n=0,1,2….
HOMOUS SERIES
ALKENE ALCHOLS CARBXIC ACIDS
FUNCTN GROUP
Carbon- carbon double bond (-C=C-)
Hydroxyl
(-C-OH)
Carboxyl
( -COOH )
HOMOUS SERIES
ALKENE ALCOLS CARBYLIC ACIDS
NAME OF MEMBER
ethene ethanol Ethanoic acid
OR propene propanol Propanoic acid
OR butene butanol Butanoic acid
Year 2007question no 10
REVISON ON thermochemistry
Exp Reactants Products Observation
I2.6 g of zinc and 50 cm3 of acid P
2.0 mol dm-3
Zinc chloride and hydrogen
gas
The temperature
of the mixture increases
II2.6 g of zinc and 50 cm3 of acid Q
2.0 mol dm-3
Zinc sulphate and hydrogen
gas
The temperature
of the mixture increases
data from Exp I and Exp II that were carried out to study the rate of reaction of zinc with two acids, P and Q.
• (i) By choosing either Experiment I or Experiment II, state the name of the acid used.
•
• (i) Write the chemical equation for the reaction of this acid with zinc. [2 marks]
(ii) Draw an energy profile diagram for the reaction in 10(a)(i). On the energy profile diagram show the:–Heat of reaction, AH–Activation energy without a catalyst, –Activation energy with a catalyst, E'
Explain the energy profile diagram.[10 marks]
∆H
E- activattion energy without catalyst
E’- activattion energy with catalyst
energy
Energy profile diagram of reaction zinc and hydrochloric acid
(ii) Explain the energy profile diagram.
∆H
(ii) Explain the energy profile diagram.
∆H
(ii) Explain the energy profile diagram.
∆H
∆H
(ii) Explain the energy profile diagram.
∆H
(ii) Explain the energy profile diagram.
∆H
SPM 2008QUESTION 8
REVISION ON Section B -
electrochemistry
Diagram 8.1 shows the apparatus set up for the electrolysis of sodium chloride solution using carbon as electrode
(a) State the factors that determine the products formed at electrode P
and electrode Q• Electrode P : Position
of ions in electrochemical series
• Electrode Q : Concentration of ions in the electrolyte.
b) Explain the reactions at electrode P and Q.
• List of ions attracted to i) electrode P: Na + , H+
ii) Electrode Q : Cl- , OH-
• Names of ions discharged at i) electrode P: Hydrogen ion ii) Electrode Q : Chloride ion
• The reason why the ions selectively discharged at :
i) Electrode P: H+ ion is lower than Na+
ion in electrochemical series
ii) Electrode Q : Cl- ion is more concentrated than OH- ion
• Half equations for each reaction
i) Electrode P: 2H+ + 2e
H2
ii) Electrode Q : 2Cl- Cl2 + 2e
END