Page 139 - Chemistry

(a) Calculate the average volume of solution B used
(b) Given that the equation for the reaction taking place is:-
Na 2CO 3(aq) + 2HX (aq) 2NaX (aq) + CO 2(g) + H 2O (l)
Calculate the concentration of solution B in moles per litre
Procedure II
3
Fill the burette to the 0.0mark with solution B. Pipette 25.0cm of solution C into a clean
dry conical flask and titrate it against solution B using phenolphthalein indicator. Repeat the
titration and fill table II below:-
Table II
1 2 3
3
Final burette reading (cm )
3
Initial burette reading (cm )
3
Volume of solution B used (cm )

(c)What is the average volume of solution B used?
(d) Calculate the concentration of solution C in :-
(i) Moles per litre
(ii) Grams per litre (K=39, O=16, H=1)
(e) Calculate the percentage of potassium chloride in the mixture
2. You are provided with:-
- Solution Y containing 0.2moles of copper (II) sulphate per litre of solution
- Solid Z
You are required to:
Determine the heat evolved when 1 mole of solid Y reacts with solid Z
Procedure
3
3
- Measure 40cm of solution Y and place it into an insulated 100cm plastic beaker
- Stir the solution with the help of thermometer and record its temperature after every ½ minute
for 1½ minutes.
- After exactly 2 minutes, add all the solid Z provided and continue stirring the mixture while
recording the temperature of solution and complete the table below:
Time ½ 1 1½ 2 2½ 3 3½ 4 4½ 5 5½ 6 6½ 7
(minutes)
Temperature
o
( C )

(b) (i) On the graph paper provided, plot a graph of temperature against time
(ii) From your graph, determine the maximum temperature change
3
(c) Given that the density of the solution is 1g/cm , determine the quantity of heat evolved
3
when 40cm of solution Y is reacted completely with solid Z
-1 -1
(specific heat capacity of solution = 4.2jg k )
(d) (i) Given that solid Z is Zinc powder, write an ionic equation of the reaction which occurs
(ii) Determine the moles of copper ions used up in the reaction
(iii) Determine the amount of heat that would be evolved if one mole of Copper
(II) ions were used up
(iv) Explain why the value obtained in this reaction is lower than the actual value?
3. I. You are provided with solid P. Carry out the tests below and write the observations
and inferences in the spaces provided

(a) Heat about one third of solid P in a clean dry test tube
3
(b) Add 10cm of distilled water to the remaining solid P in a boiling tube and shake.
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