KAIRI HIGH SCHOOL
END OF TERM 2 EXAM - FORM 4 – 2017
CHEMISTRY PAPER 2
Name: ______Adm. No. _____ Class: _____
1. Study the information below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
Element / Atomic No. / Melting point oCL
M
N
Q
R / 11
13
14
17
19 / 97.8
660
1410
-101
63.7
a) Write the electron arrangement for the ions formed by element M and Q.
M – 1mk
Q - 1mk
b) Select an element which is;
i) the most reactive non-metal - ______1mk
ii) a poor conductor of electricity - ______1mk
c) In which period of the periodic table does element R belong? ______1mk
d) Element R loses its outermost electron more readily than L. Explain. 2mks
e) Describe how a solid mixture of the sulphate of element R and lead sulphate can be separated into solid samples. 3mks
2. The set up below was used to prepare hydrogen gas.
a) Complete the diagram to show how a dry sample of hydrogen gas can be collected. 2mks
b) Write an equation for the reaction which takes place when hydrogen gas
burns in air. 1mk
c) 1.2 litres of hydrogen gas was produced at room temperature and pressure when 3.27g of Zinc were used. Determine the relative atomic mass of Zinc. (Molar gas volume is 24 litres) 2mks
d) State two industrial uses of Hydrogen gas. 1mk
i)
ii)
II. Study the experiment below and answer the questions that follow. The gas produced ignites spontaneously.
i) Which metal is used above? ______1mk
ii) Which gas was produced? ______1mk
iii) What will be the colour of phenolphthalein indicator in the resulting
solution? ______1mk
3. a) State two differences between chemical and nuclear reactions. 2mks
Chemical reaction / Nuclear reactioni)
ii)
b) Below is a radioactive decay series starting from 214 and ending at 206
83 82
Study it and answer the questions that follow.
214 210 210 210
83 81 82 83
Step IV
206 210
82 84
i) Identify the particles emitted in steps III & IV. 2mks
III –
IV –
ii) Write the nuclear reaction for the reaction which takes place in step I. 1mk
c-i) Define the term half life. 1mk
ii) 800g of a radioactive isotope decays to 50g in 100 days. Determine the half life of this isotope. 2mks
d) State two medical uses of radioactive isotopes. 1mk
i)
ii)
4. 2.5g of a metal carbonate was reacted with excess 2M nitric (V) acid. The volume of carbon (IV) oxide produced measured and recorded at 10 second intervals. The results were recorded as shown in the table below.
Volume of gas (cm3) / 0 / 90 / 150 / 210 / 280 / 305 / 390 / 450 / 480 / 480 / 480Time in sec. / 0 / 10 / 20 / 30 / 40 / 50 / 60 / 70 / 80 / 90 / 100
a-i) 0n the grid provided, plot a graph of volume (vertical axis) against time.
Label it as A. 3mks
ii) From your graph, determine the rate of reaction between 25 seconds and 40 seconds. 2mks
iii) 0n the same grid, sketch a curve that would be obtained if the same experiment was repeated using excess 1M nitric (V) acid. Label it as B. 1mk
b-i) Write a balanced chemical equation for the reaction between the metal carbonate and the 2M nitric (V) acid. 1mk
ii) Given that Carbon (IV) 0xide was measured at room temperature and pressure, work out the relative atomic mass of metal M.
MGV = 24 dm3, C = 12, 0 = 16. 3mks
5. Use the information in the scheme below to answer the questions that follow.
P
K2Cr207 step II
Hydrogen step I Butan-1-01 burn Products
step III
Step IV
Conc H2S04 CH3CH2CH=CH2 ______H2/Nickel catalyst
+ H20 step VI Q
Butan-1-01
Step VII
CH3C00CH2CH2CH2CH3
a) Name the substance P - ______1mk
b) Give the structure and name of compound Q -
Structure - 1mk
Name - 1mk
c) Write the equation for the chemical reaction in step III. 1mk
d) Name the reagents and condition necessary for the reaction in;
i) Step IV.
Reagents - ½ mk
Conditions ½ mk
ii) Step VII,
Reagents - ½ mk
Conditions ½ mk
e) What name is given to the reactions in;
i) step VII 1mk
step II 1mk
f) RC00 –Na+ and RCH20S03-Na+ represents two types of cleansing agents.
i) Name the class of cleansing agent to which each belongs. 1mk
RC00-Na+
RCH20S03-Na+
ii) Which one of the two cleansing agents is likely to pollute the environment? Explain. 2mks
6. Study the diagram below and use it to answer the questions that follow.
i) Name the liquids; 1mk
A - B –
ii) Suggest a suitable reagent that can be used as solid D. ______½ mk
iii) State the role of solid D. ½ mk
iv) Write a balanced chemical equation for the reaction in the conical flask. 1mk
v) Explain why solid C collects further away from the heated aluminium metals.
vi) In the combustion tube above, 0.675g of aluminium metal reacted completely with 1800 cm3 of chlorine gas at room temperature. Determine the molecular formula of solid C, given that the relative formula mass is 267.
(Al = 27, Cl = 35.5, molar gas volume at rtp = 24.0 litres) 2mks
b) The reaction between hot concentrated sodium hydroxide and chlorine gas produces sodium chlorate (V) as one of the products.
i) Write the equation for the reaction. 1mk
ii) Give one use of sodium chlorate 1mk
c) Explain the difference between bleaching by chlorine and bleaching by sulphuric (IV) oxide gases. 2mks
7. The flow chart below shows a sequence of reaction involving a mixture of two salts, Mixture M. Study it and answer the questions that follow.
Mixture M
Step I i) addition of water
ii) Filtration
solution N Solution P
step II step IV i) Acidified Barium Nitrate solution ii) Filtration
Heat
Black solid Q and a gas
that forms a white
precipitate when
bubbled colourless White solid
through calcium solution
Hydroxide step VII excess aqueous
step III ammonia
Dilute sulphuric White precipitate
(VI) acid which dissolves to form
a colourless solution
Blue solutions
Step IV Excess aqueous step V magnesium
Ammonia powder
Deep blue solution 1 Products
a) Write the formula of the following.
i) Anion in solid Q 1mk
ii) The two salts present in mixture M. 2mks
b) Write ionic equations for the reaction in step VI. 1mk
c) State and explain the observations made in step (V). 3mks
d-i) Starting with lead (II) oxide describe how a pure solid sample of lead sulphate can be prepared in the laboratory. 2mks
ii) How can one determine the lead sulphate prepared is pure? 2mks
8. The diagram below show a set up to determine the standard electrode potentials (Eo) of zinc.
a) Label part B. ______1mk
b) Write the equation that takes place at the zinc electrode. 1mk
c) 0n the diagram show direction of electron flow. 1mk
d) Study the standard electrode potentials given below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
E ( ) volts
P+(aq) + e- P(s) -2.92
M2+(aq) + 2e- M(s) -0.76
T2+(aq) + 2e- T(s) +0.34
W2(g) + 2e- 2W-(aq) +1.36
N+ + e- N(s) +0.80
i) Identify the strongest oxidizing agent - 1mk
ii) Which two of the above elements would produce the largest e.m.f? 1mk
iii) Calculate the e.m.f. of the cell made by metals M and N. 2mks
iv) Write a cell representation for the electrochemical cell formed in (iii)
above. 1mk
v) Explain whether it would be advisable to store a nitrate solution of metal
in a container made of metal P. 2mks
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