Page 247 - Chemistry

II a)(i) Curve I Reason: F increases as E decreases.

(ii) Equilibrium is achieved.

8. Q = 40000 x 60 x 60 = 144000000c
Mass of Al = 144000000 x 27  1
3 x 96500
= 13.43kg  1

9. a) Hydrochloric acid is a weaker oxidizing agent which cannot oxidize copper to form
Nitrogen (VI) Oxide gas
b) It increases  1 mark
Molecules/ particles acquire the necessary activation energy// Kinetic energy. This
increases the frequency of collisions hence the rate of reaction  ½ mark
c) Graph - Scale 1 mark with axis well labeled
- Plotting + all points correct 1 mark
5 correct points ½ mark
Less than 5 points 0 mark
Correct smooth curve 1 mark
TOTAL 3 marks

3
d) i) 360cm Read correct value from graph + .05
-
3
ii) 40cm = Value from graph + .05
-
Read where it levels off

10. (a) 260 – 85 = 175 = 87.5cm 3/mn;
2 2
(b) 4 ½ min;
(c) Zinc was used up / H 2SO4 used up;

11. (a) Platinum / Platinum Rhodium
(b) Pressure -9atm ( ½ mk)
o
o
Temp – 700 C – 900 C ( ½ mk)
(c) Reaction is exothermic

12. (a) (i) Will increase;
(ii) Decrease;
13.
 Dissolve solid √ ½ YSO 4 to obtain √ ½ YSO 4 in solution,
 Dissolve √ ½ X(NO 3) 2 in water to obtain √ ½ X (NO 3) 2 solution. 3
 Mix the two above solutions
 Filter to obtain XSO 4 solid residue, rinse with water and dry by heating √ ½
 under asbestos pad.

14. R (s) + S 2+ (aq) R 2+ (aq) + S (s) √1 (1 mk)
E.m.f = 0.47 – (-2.04)
= -0.47 + 2.04 2
= 1.57V √1 (1 mk)

www.kcse-online.info 246