Page 146 - Chemistry

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(ii) Pipette 25cm of solution L into 250cm conical flask and add 2 drops of phenolphthalein
indicator to it and titrate with solution N.
(iii) Record your results in the table below
(iv) Repeat the experiment twice to obtain consistent readings and complete the table

Table 1
Titration 1 2 3
3
Final burette reading (cm )
3
Initial burette reading (cm )
3
Volume of solution N used (cm )

(a) Calculate the average volume of solution N used
(b) Determine:-
(i) The concentration of sodium hydroxide in one litre of solution L
(Na =23, O= 16, H= 1)
(ii) Write the equation of the reaction taking place
(iii) The number of moles of anhydrous carbohydrates oxalic acid in one litre of the
solution N
(iv) The relative formula mass of anhydrous oxalic acid, solution N (C = 12, H=1, O = 16)
(v) The number of moles of water of crystallization in one mole of oxalic acid

2. You are provided with solid K, a boiling tube and a thermometer. You are required to
determine the solubilities of solid K, at various temperatures.
Procedure:-
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(a) Carefully transfer all the 4.0g of solid K into a clean boiling tube and add 10cm of
distilled water from a burette.
(b) Heat the boiling tube and its contents gently with shaking until all the solid dissolves.
(Do not spill the solution during heating.) Stop heating when all the solid dissolves.
See the diagram below:-

Thermometer

Test-tube holder

Boiling tube

Heat
(c) Gently stir the solution using the thermometer and record the temperature at which
crystals appear. (The crystals appear as small shining particles)
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(d) Using a burette add 2.5cm of water to the solution and heat until all the solid dissolves.
Repeat procedure(c)

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