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Zinc metal and hydrochloric acid react according to the following equation
Zn(s) + 2HCl(aq) ZnCl(aq) + H2(g)
1.96g of zinc were reacted with 100cm3 of 0.2M Hydrochloric acid,
(a) Determine the reagent that was in excess
(2mks)
(b) Calculate the total volume of hydrogen gas that was liberated at S.T.P conditions
(Zn = 65.4, molar gas volume = 22.4 litres at S.T.P)
(2mks)
2. Calculate the mass of nitrogen (IV) oxide gas that would occupy the same volume as 10g
of hydrogen gas at the same temperature and pressure. (H = 1.0, N = 14.0, O = 16.0)
(2mks)
3. Urea, (NH2)2CO is prepared by the reaction between ammonia and carbon(IV) oxide
In one process, 340kg of ammonia were reacted with excess carbon (IV) oxide.
Calculate the moles of urea that were formed. (H = 1.0, C = 12. 0, N = 14.0, O = 16.0)
(2mks)
3
4. In a filtration experiment 25cm3 of solution of sodium hydroxide containing 8g per litre was
 required for complete neutralization of 0.245g of a dibasic acid. Calculate the relative
 molecular mass of the acid. (Na = 23.0, O = 16, H = 1)
(3mks)
5. 12.0 cm3 of methane and 48cm3 of oxygen were exploded together. The final volume measured
under the original conditions was 36.0 cm3 neglecting the water formed. 24.0cm3 of this was
unused oxygen. Show the ratio of reacting volume of the gases referred to and gaseous products
formed.
(2marks)
6. 4. 9 g a tribasic acid was dissolved in water and the solution made up to 500cm3. If the
concentration of the hydrogen ions in the solution is 0.3M, calculate the relative molecular mass
of the acid.
(3marks)
7. The mass of 1 dm3 of gas X at room temperature and pressure is 2.667g. Determine the relative
molecular mass of the gas (molar gas volume at r.t.p =24dm3).
(2marks)
8. A solution was made by dissolving 7.5g of sodium hydroxide containing inert impurities
in water and making it to 250cm3 of solution. If 20cm3 of this solution is neutralized
exactly by 13cm3 of 1M hydrochloric acid, calculate the percentage purity of sodium
hydroxide.
(Na=23; O=16; H=1)
(3mks)
9. a) An oxide of nitrogen contains 30.4% nitrogen. Its density at s.t.p is 4.11g/dm3.
Determine the molecular formula of the compound.
(N=14; O=16; moles gas volume = 22.4dm3)
(2mks)
5
b) Magnesium ribbon was burnt in a gas jar of nitrogen. A few drops of water were
added to the solid formed in the jar. provide equation for the second reaction.
(1mk)
 ………………………………………………………………………………………………………
10. In a experiment, 10.6g of a mixture of Anhydrous Sodium Carbonate and Sodium Chloride
were dissolved in water to make 100cm3 of a solution required 20.0cm3 of 0.5M Hydrochloric acid
solution for complete neutralization. What is the mass of Sodium Carbonate in the mixture?
(Na = 23.0, C = 12.0, O = 16.0, Cl = 35.5) (3mks)
11. For the reaction
Na2SO3(s) + 2HCl(aq) 2NaCl(aq) + SO2(g) + H2O(l)
Given that 25.2g of Na2SO3 were made to react with 700cm3 of 0.5M HCl, which reagent
was in excess? (3mks)
12. 9.42g of an organic acid RCOOH is dissolved in 600cm3. 25.0cm3 of this solution was
found to require of 0.207M potassium hydroxide solution for complete neutralization.
( C = 12.0, O = 16.0, H = 1.0)
i) Determine the formula mass of the acid
6
 (2mks)
ii) Hence the value of R
(1mk)
13. 25.0cm3 of 0.12M potassium hydroxide solution required 30.0cm3 of a solution of a
dibasic acid (H2Y) for complete neutralization. The acid contained 3.15g per 500cm3 solution.
Calculate:
(a) The molarity of the acid solution (1½mks)
(b) The relative formula mass of the acid.
(1½mks)
7
14. Zinc Sulphate can be used as a dietary supplement in cases of suspected zinc deficiency. The
compound crystallizes as anhydrated salt and is readily water soluble.
(b) In a simple experiment to determine the extent of hydration, a technician carefully
heated 3.715g of crystals to a moderate temperature until no further loss in mass
occurred. The anhydrous zinc had a mass of 2.08g.
(i) How many moles of zinc are there in 2.08g of anhydrous zinc Sulphate? (Zn
= 65, O = 16, S = 32, H = 1)
(2mks)
(ii) How many moles of water were lost? (2mks)
(iii) Determine the value of n in the formula ZnSO4. nH2O. (2mks)
(c) The daily intake of zinc in Kenya is 15mg per adult person.
(i) What mass of zinc Sulphate crystals would need to be taken to obtain this
intake? (2mks)
(ii) If this is taken via a 5ml dose of aqueous zinc Sulphate, calculate the
concentration of this solution in molcm-3 of the hydrated salt. (2mks)
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