KITUI WEST DISTRICT JOINT EVALUATION TEST
CHEMISTRY – PAPER2

MAKING SCHEME

1. i)
|Element |Ion |Valency |Oxidation number |
|X |X3+ |3 |+3 |
|Y |Y2+ |2 |+2 |
|W |W- |1 |-1 |
|Z |Z3- |3 |-3 |

½ for each correct answer (Total 6 mks)

ii) X, W √1and Z. They have equal number of energy levels. √1

iii) X and Y√1. They have delocalized electrons. √1

iv) X.√1it has more delocalized electronics. √1

v)

√2

2. i) Fermentation √1

ii) I. Ethene gas. √1 II. Ethane gas √1 III. Carbon (IV) oxide gas√1 IV. Hydrogen gas.√1

iii) I. C2H4(g) + Br2(g) CH2BrCH2Br√1 II. 2C2H6(g) + 7O2 4CO2(g) + 6H2O(L)√1 III. 2H2O(L) + 2Na(s) 2NaOH(aq) + H2(g)√1

iv) It pollutes the land.√1 It is non-biodegradable. √1

v) Calcium carbonate.√1(Rej the formula).

vi) Used to convert edible oils to fats. √1

3. i) I. Zinc blende √1 II. Calamine.√1

ii) I. Carbon (IV) oxide gas.√1 II. Sulphur (IV) oxide gas. √1

iii) I. Zinc oxide. √1 II. Carbon √1

iv) ZnO(s) + C(s) Zn(s) +CO(g) √1

v) To decompose to Calcium Oxide which combines with silica the main impurity in the Zinc ores.√1

vi) Used to galvanise iron Used in making dry cells. Used in making alloys.

vii) Contact process for manufacture of Sulphuric acid. √1 Solvay process for manufacture of Sodium Carbonate. √1

4. (a)i) A √1 ii) C2. √1It has an EØ value of 0.00V.√1 iii) B2+(aq) + A(s) A2+(aq) + B(s) √1 iv) EØ = EØ- EØ = (+0.34 - - 0.45) V√1