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2010 KCSE Chemistry Trial P2-001

Name……………………………………………………………. Index

No……………………………..

School…………………………………………………………… Candidate’s sign…………………….

Date………………………………….

233/2

CHEMISTRY Paper 2Theory July/August 20102 Hours

RARIEDA DISTRICT JOINT EVALUATION TEST – 2010Kenya Certificate of Secondary Education (K.C.S.E)

233/2

CHEMISTRY Paper 2Theory July/August 20102 Hours

INSTRUCTIONS TO CANDIDATES.

1. Write your name and index number in the spaces provided above2. All working must be clearly shown3. Mathematical tables and electronic calculators may be used.

FOR EXAMINER’S USE ONLY.

QUESTION MAXIMUM

SCORE

CANDIDATES SCORE

1 12

2 12

3 10

4 11

5 13

6 7

7 7

8 8

80

©2010 Rarieda District Academic Committee Chemistry 233/2 Turn over1

This paper consists of 16 printed pages. Candidates should check the question paper toEnsure that all the pages are printed as indicated and no questions are missing.

1. I. Below is grid which represents part of periodic table. Use it to answer the questions that follow. The letters do not represent the actual symbols of the elements.

J N O QK L M P S

a) What name is given to the group of elements to which L belongs? ( ½ mk)………………………………………………………………………………………………

b) What name is given to the elements that occupy the shaded region? ( ½ mk)………………………………………………………………………………………………

c) How would the boiling points of element Q and R compare?Explain. (2mks)

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d) Give the name and the formula of the products formed when oxide of M reacts with excess sodium hydroxide solution. (2mks)

(i) Name………………………………………………………………………………………………

(ii) Formula

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(iii) Oxide of M is also found to react with dilute hydrochloric acid. What type of oxide is M oxide? (1mk)

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e) Give one use of element S and state the property that makes it suitable for that use.(2mks)

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II. Study the data in the table below and answer the questions that follow the letters do not represent actual symbol of the elements.

Element Atomic No. MP (°C) BP °C Ionic radius

C 11 98 890 0.095

D 12 650 1110 0.065

E 13 660 2470 0.050

F 14 1410 2360 0.041

G 15 44.2 280 0.034

H 16 113 445 0.184

I 17 -101 -35 0.181

J 18 -189 -186

a) State the structure of chlorides of elements D and F. (1mk)

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b) Explain the following observations in terms of structure and bonding:(i) There is an increase in boiling points from C to E. (1mk)

(ii) Element F has a high boiling point. (1mk)………………………………………………………………………………………………

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(iii) There is a decrease in boiling point from H to I. (1mk)………………………………………………………………………………………………

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2. I Study the flow chart for the industrial manufacture of ammonia given below and answer

the questions that follow.

a) State the purpose of the unit labeled S. (1mk)

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b) What is the function of the circulating pump? (1mk)

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c) Suggest the source of the raw materials. (2mks)

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d) Name two impurities removed during the purification of hydrogen and nitrogen. (1mk)

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e) In what state is the final product collected.

Explain? (2mks)

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II Below is a set – up in the preparation of a particular salt. Study it and answer the questions

that follow.

a) Explain the observation made in the combustion tube when dry hydrogen Chloride gas is

passed instead of dry chlorine. (2mks)

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b) Identify solid K (1mk)

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c) What property makes solid K to be collected in the flask as shown below. (1mk)

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d) State the purpose of anhydrous calcium Chloride as shown in the set – up above. (1mk)


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3. a) Name the heat change represented by H in the process represented below.

Na(s) Na (g) H = +ve (1mk)

b) The table below gives some bond energies of some bonds.

Bond Bond energy (kJ mol )

H – H 435

Cl – Cl 243

H – Cl 431

Calculate the enthalpy changes for the reaction.

H 2(g) + Cl2(g) 2 HCl(g) (2mks)

c) i) Define enthalpy of formation of a substance. (1mk)


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ii) Given that

Calculate the molar heat of combustion of butane ( C4H10) (2mks)

d) Study the following exothermic reactions involving enthalpy of neutralization

I NaOH(s) + HCl(aq) NaCl(aq) + H2O(l) H1

II NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) H2

i) Identify the reaction with a higher H value. Giving a reason for your answer. (2mks)

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ii) The atomic numbers of Li and K are 3 and 19 respectively.

Li+(g) + (aq) Li+

(aq) H3 = -519

K+(g) + (aq) K+

(aq) H4 = -322

Study the equations above and explain why H3 is larger than H4. (2mks)

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4. Use the standard electrode potentials given below to answer the questions that follow.

Ag+(aq) + e- Ag(s) + 0.80……….(i)

Cu2+(aq) + 2e- Cu(s) + 0.34 ……..(ii)

Pb 2+(aq) + 2e Pb(s) -0.13………(iii)

Zn2+(aq) + 2e- Zn(s) -0.76………(iv)

a) Select two half – cells which when combined will give the lowest workable cell

(lowest (e.m.f)) (1mk)

b) Can a solution of silver nitrate be stored in a container of Zinc? (2mks)

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c) An iron jug was electroplated using Chromium. The chromium electrode and iron jug

were thoroughly cleaned and weighed before being dipped into the electrolyte. Why was

cleaning necessary? (1mk)

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d) A current of 0.75 Amperes was passed through the solution for one hour and four minutes.

The mass of chromium deposited on the jug was 0.52g

(1Faraday = 96500C Cr = 52)

(i) Calculate the quantity of electricity passed. (2mks)

(ii) How many moles in Chromium were deposited? (1mk)


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(iii) Calculate the quantity of electricity in coulombs required to deposit one mole of

Chromium. (2mks)

(iv) Deduce the charge of the Chromium ion. (2mks)

5. The scheme below shows various reactions and process for some organic compounds.

Study it and answer the questions that follow.

a) Name process I and name any other product formed in the process. (2mks)

(i) Process I


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(ii) Product

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b) Name the reagent and condition required in process II. (2mks)

Reagent

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Condition

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c) i) Give the name of the product formed in process III. (1mk)

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(ii) State two conditions required in process III. (1mk)

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(iii) Give one characteristics property of the product formed in process III (1mk)

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d) Name the catalyst and reagent required in step IV.

Catalyst (2mks)

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Reagent


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e) Give any one use of the product formed in process (V) (1mk)

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f) Name process (VI) (1mk)

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g) Process VII requires a catalyst and goes through an intermediate product.

Name:-

(i) The catalyst (1mk)

(ii) The intermediate product. (1mk)


6. The solubility in grams of sodium Nitrate in 100g of water is given in the table below for various

temperature.

Temperature 10 20 30 40 50 60 70 85

Solubility / 100 g of water 73 80 88 96 104 114 124 150

(i) Plot a graph of solubility of sodium nitrate against temperature. (4mks)


(ii) Determine the temperature at which the solubility of the salt is 65g per 100g of water.

(1mk)

(iii) Given 100g of a saturated solution of sodium nitrate at 100°C.

Calculate the mass of solute in the solution. (2mks)

7. The flow chart below represents the main steps in the manufacture of sodium carbonate

a) Name substances labeled A – D (2mks)

A ………………………………………………………………………………………

B ………………………………………………………………………………………


C ………………………………………………………………………………………

D ………………………………………………………………………………………

b) Identify substance E and write a chemical equation for the reaction in the kiln. (2mks)

Substances E…………………………………………………………………………

Equation………………………………………………………………………………

c) Explain the need of large amounts of water in this experiment. (1mk)

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d) Name the by – products that are recycled.

e) Why is recycling important. (1mk)

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8. The flow chart below outlines some of the process involved in extraction of copper from copper

pyrites.

Study it and answer the questions that follow.


(i) Name gas K ( ½ mks)

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(ii) Write an equation for the reaction that takes place in the first roasting furnace. (1mk)

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(iii) Write the formula for the cation present the slag M. ( ½ mk)

(iv) Identify gas P. ( ½ mks)

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(v) What name is given to the reaction that takes place in chamber N? Give a reason for your

answer. (1½ mk)

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b) Below is a simplified diagram of the Downs cell in which sodium metal is manufactured.


(i) Identify electrolyte X and gas Y. (1mk)

Electrolyte X ……………………………………………………

Gas Y ………………………………………………………….

(ii) Give two properties of sodium that make it possible to collect as in (iii) above. (1mk)

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(iii) The cathode is made of steel, but the anode is made of graphite, although steel is a better

conductor. Why is this? (1mk)

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(iv) How would you obtain sodium hydroxide pellets from sodium amalgam? (1mk)

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