Page 236 - Chemistry

1000
= 0.005moles
mole ration acid : base
2 : 1
moles of Na 2CO 3 = 0.005
2
= 0.0025
Molarity of Na 2CO 3 = 0.0025 x 1000
20
= 0.125M

17. a) i) I) Heating √1
II) Filtration. √1
ii) Effervescence √1 / Bubles.
2+
-
iii) Zn (aq) + 2OH (aq) Zn(OH) 2(s) √1
iv) Pass the water vapour over white anhydrous√1 Copper (II) suplhate. It turns blue. √½
b) i) R is a mixture of sulphur √½ and insoluble√½ salt. It forms √1 a filtrate and residue in
filtration of mixture
2-
ii) Carbonate √1 / CO 3 √1
+
It produces CO 2 on reaction with H
3+
2+
iii) Zn √1 Al √1
18. a) The quantity of a substance in grammes that can dissolve in 100g of water at a given
temperature

b) i) Fractioned crystallization
ii)
iii)
I 26C
II 18g

iv) 1 mole of salt M _______ 132g
18x1 / 132 = 0.13863636 moles
Concentration = 1000 x 0.13863636
100
= 1.386M
v) L = 20g M= 19g
38-20=18
22-19= 3+
Total 21 g
19. (a) (i) A saturated solution is one which cannot dissolve more solute at that particular
temperature.
1 (1 mk)
(ii) Solubility of a soluble is the amount of grams of solute present in 100g of water at that
particular temperature. 1 (1 mk)

(b) (i) Mole = M x V
1000

0.1 x 24 1 = 0.0024 moles1 (2 mks)
1000
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