Page 171 - Chemistry

carbonate.
(g). Determine the mass of sodium carbonate that reacted with the acid. (Na= 23, C= 12, 0= 16).

2. You are provided with the following.
(i). 1.2g Magnesium powder, solid M
(ii). 0.02M copper (ii) sulphate, solution K
You are required to determine the molar enthalpy of displacement for the reaction
between
magnesium powder and copper (II) sulphate solution.
Procedure
3
Measure out 100cm of solution K into a plastic beaker.
Measure the temperature of this solution at every minute for four minutes. Add the entire amount
of solid M to the contents of the plastic beaker at the fourth minute. Stir with the thermometer.
Record the temperature after every half-a- minute in table II below.

Table II

1
Time 0 ½ 1 1 ½ 2 2 / 6 3 3 ½ 4 4 ½ 5 5½ 6 6½
(min)

o
Temp.( C)

o
(a). Draw the graph of temperature ( C) against time, t (in minutes) ) Use your graph to
get the temperature rise.
(b). Calculate the heat lost by the solution
-1
3
-I,
(Specific heat capacity of solution = 4..2Jg K density of solution = 1g/cm )
(c). Write an ionic equation for the reaction.
(d). Calculate the number of moles of :
(i). Copper (ii) ions in the original solution.
(ii). Magnesium added to the copper (ii) sulphate solution
(iii). Copper (II) ions displaced by magnesium powder.
(Mg = 24, Cu = 63.5, S = 32, O = 16)
(e). Calculate the molar heat of displacement of copper (II) ions by magnesium powder.
(f). Comment on the value of the molar heat if ion powder had been used instead magnesium
powder . Explain.
(a). (i)You are provided with solid J.
(ii). To the filtrate above, dip a clean metallic spatula and burn a drop of the filtrate
on it with a non-luminous flame.
(iii). Divide the filtrate into two equal populations.
st
I. To the 1 portion add 2m lead (ii) nitrate.
II. To the second portion add 3 -5 drops of 20% 20 – Volume hydrogen peroxide
3
(iv). To the resulting mixture in (ii) above, add about 1cm of sodium thiosulphate
solution Q. From the tests carried out above identify.
(i). Cation
(ii). Anion

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