Page 287 - Chemistry

White precipitate dissolves √½
-1
on boiling and re-appears √½ Cl √1
on cooling

Q.3 a) Observations Inferences

Burns with yellow √1 smoky/ C = C or -C≡C-, Long chain
sooty flame hydrocarbon, unsaturated
organic compound, hydrocarbon with high
C : H ratio. Any 1 = 1 mk

b) Observations Inferences

Dissolves√1 to form a Polar organic √1 compound / polar substance
colourless solution.

i) Observations Inferences
KMnO 4√1 decolorized / changes C = C -C ≡C-
from purple to colourless.
2 = 1 mk 1 = ½ mk

ii) Observations Inferences
O

+
+
Methyl Orange turns √1 √1 H / H 3O / - C
pink / red. O - H

Question 1.
Table 1
Distributed as follows:
(i) Complete table
Values must be ±0.2 of each other
(ii) Decimal place
Values should be n 1d.p or 2d.p consistently used.
(iii) Accuracy
Compare the school value to any of the readings and award as follows:
If ±0.1 award 1mk
± 0.2 award ½mk
Outside 0.2 award 0mk
(iv) Principle of averaging
- Award 1mk for consistent value only.
- Penalize ½mk for rounding of the answer to 1d.p unless it divides exactly.
- In consistent values averaged award 0mk
(v) Final answer value to the school to compare the average value to the school value:-
If ±0.1 award 1mk
If ±0.2 award ½mk
If outside award 0mk

Calculations
(a) Titre 1 + Titre II + Titre III = Answer
3

www.kcse-online.info 286