THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL
CERTIFICATE OF SECONDARY EDUCATION EXAMINATION
032/1 CHEMISTRY 1
(For Both School and Private Candidates)
Time: 3 Hours Thursday, 06th November 2014 p.m.
Instructions
Atomic masses:
H = 1, C = 12, N = 14, Na = 23, S = 32, O = 16, Al = 26, Cl = 35.5 Ca = 40, Mn = 55, Fe = 56, K = 39.
Avogadro’s number = 6.02 x 1023.
GMV at s.t.p. = 22.4 dm3.
1 faraday = 96,500 coulombs.
Standard pressure = 760 mm Hg.
Standard temperature = 273 K.
1 litre = 1 dm3 = 1000 cm3.
Answer all questions in this section.
1. For each of the items (i) – (x), choose the correct answer from the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) An element in the periodic table with atomic number 18 belongs to which of the following?
(ii) The ionic equation when aqueous ammonium chloride reacts with sodium hydroxide solution is represented as:
(iii) The reason why white anhydrous copper (II) sulphate turns blue when exposed in atmosphere is that it,
(iv) Chemical change means;
(v) If a stead current of 2 amperes was passed through an aqueous solution of iron (II) sulphate for 15 minutes, then the mass of iron deposited at the cathode will be:
(vi) 10 cm3 of 0.4 M sodium hydroxide are added to 40 cm3 of 0.2 M hydrochloric acid. The resulting mixture will be
(vii) The only metal which does not react with dilute hydrochloric acid is
(viii) Which of the following solutions is the most concentrated?
ix) Alcohols react with carboxylic acids to form a group of organic compounds called
(x) Which of the following statement is true about water gas?
2. Match the items in List A which the responses in List B by writing the letter of the correct response beside the item number in the answer booklet provided.
LIST A | LIST B |
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Answer all questions in section.
3. (a) (i) Why chemistry laboratory exits open outward?
(ii) State the uses of any four items found in a First Aid Kit.
View Ans(b) (i) Arrange the following metals in order of increasing reactivity; zinc, magnesium, calcium, copper and mercury.
(ii) Which one of the metals in (b) (i) above reacts with steam to form an oxide which is white when cold and yellow when hot?
View Ans4. (a) 20 cm3 of a solution containing 7 g dm-3 of sodium hydroxide were exactly neutralized by 25 cm3 of 0.10 M hydrochloric acid. Calculate the concentration of sodium hydroxide in moles per dm3.
View Ans(b) Give two examples in each of the following solution.
(i) Gaseous solution.
(ii) Solid solution.
View Ans5. (a) Study the following part of the periodic table and List down the names of all the missing elements. Table 1
H |
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| He |
Li | Be | B |
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| F |
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| Al | Si | P | S | Cl | Ar |
(b) (i) Write the reaction equations involved in the industrial manufacturing of sulphuric acid starting with sulphur dioxide in the contact process.
(ii) Explain why sulphur trioxide is not dissolved directly in water to obtain sulphuric acid in contact process.
View Ans
6. (a) With the aid of chemical equations, explain what will happen when aluminium chloride reacts with water.
View Ans(b) A student accidently broke a beaker containing copper (II) sulphate crystals. He decided to separate the blue crystals from the small pieces of glass by first dissolving the mixture and then filtering. What were his next steps?
View Ans7. (a) Table 2 gives some information about the composition of three samples of water from wells in Kahama, Maswa and Bukombe districts.
Table 2
Ions | Mineral content of water in mg per litre | ||
Kahama | Maswa | Bukombe | |
Calcium, Ca2+ | 28 | 82 | 18 |
Magnesium, Mg2+ | 14 | 41 | 13 |
Chloride, Cl- | 53 | 7 | 22 |
Sodium, Na+ | 7 | 143 | 39 |
Hydrogencarbonate, HCO3- | 281 | 5 | 93 |
Sulphate, SO42- | 2 | 14 | 16 |
(i) State two ways in which these ions get into the samples of water.
(ii) Giving two reasons, state the hardest sample of water.
(iii) State two ways that can be used to remove ions in (ii).
View Ans(b) State and describe the type of reaction in the following chemical equations:
(i) Fe(s) + CuSO4(aq) à FeSO4(aq) + Cu(s).
(ii) Na2SO4(aq) + BaCl2(aq) à BaSO4(s) + 2NaCl(aq).
View Ans8. The following are the general structural formulae of certain organic compounds: R-OH, R-COOH, and RCOOR.
(a) Name the:
(i) Homologous series represented by R-OH, R-COOH and RCOOR.
(ii) Functional groups represented by R-OH and R-COOH.
(c) When a burning splint is introduced into a gas jar containinakes use of these two properties? 9. (a) Differentiate between: (i) A base and an alkali. (ii) Atom and isotopes. (b) An organic compound P consist of 52.2% of carbon, 13% of hydrogen and 34.8% of oxygen. The vapour density of P is 23. Calculate the molecular formula of the compound P and write possible isomer(s) from the molecular formula determined. 10. (a) Aluminium reacts with oxygen to form aluminium oxide. How many grams of potassium chlorate would be heated to produce enough oxygen to form 5.1 g of aluminium oxide? (b) The preparation of chlorine gas can be represented by the following equation: MnO2 + 4HCl à MnCl2 + 2H20 + Cl2. How many moles of HCl are needed to react with 25 g of MnO2? 11. (a) (i) List four effects of excessive nitrogen to plants. (ii) State two ways through which soil nitrogen can be lost. Answer all questions in this section. 12.Assume that you are a chemist in a chemical plant that deals with the production of chlorine gas You want to produce 100 litres of chlorine gas per hour so that you can reach the company’s goal of producing 2400 litres every day. What current of electricity will you allow to flow per hour? 13. Describe five causes and effects of soil pollution.SECTION C (26 Marks)