Chemistry revision presentation on section b dan c past year paper = ogos 2011

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