Page 249 - Chemistry

23. - CB 2
- Ionic bond

24. - Intensity of red-brown fumes increases.
- High temperature vapourizes liquid nitrogen tetra-oxide to form nitrogen (IV) oxide that
is red-brown.

25. a) Curve 1

b) After sometime, the rate of formation of CaCL 2 or rate of depletion of CaCO 3 become to low
that cant be evaluated

26. a) Equilibrium shifts o the left, more CO 2 formed
(Increase in pressure favors reaction producing fewer molecules)
b) Equilibrium shifts to the left, more CO 2(g) formed

27. The solution turns yellow. Equilibrium shifts to the left when NaOH is added, the
+
–
OH ions react with H ions forcing more of cr2 O 72- and H 2O to react forming more
+
2-
H and crO4 ions the reaction particles causing higher rate of reaction and twice shorter
time√ ½

28. (i) B ; The acid had higher concentration (½mk)
(ii) The rate of reaction is initially high (½mk) because of high concentration
of the reactant but decreases ( ½mk) steadily as the concentration also decreases.
29. Yellow/brown colour of bromine water ((½mk) fades or becomes colourless because
-
+
sodium hydroxide solution provides OH ions which reacts with H ions to form water ( ½mk)
shifts the equilibrium to the right

Electrochemistry

1. i) Carbon – carbon/ platinum – carbon
ii) - The concentration of magnesium sulphate increase
- Hydrogen and oxygen given off at the electrodes reduce the water content
2+
2. Cu + 2c- __________ Cu (s)
Mass =
1.48 = 63.5 x I x 2.5 x 60
2 x 96500

I = 1.48 x 2 x 96500
63.5 x 2.5 x60
= 29.988 A
3. a) Anode is electrode A (1 mk)
B is cathode
+
b) 2H (aq) + 2e- _________ H 2 (g)

c) The acid becomes more
4. i) 200 X 58 X 60 C _______________ 64.8g  ½
9500C ____________________ 27g ½

27 X 200 X 58 X 60  ½ = +3  ½
64.8 X 96500

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