All your burette readings (initials and final) as well as the size of your pipette must be recorded but no account of experimental procedure is required. All calculations must be done in your answer booklet
(a) What difference in physical properties enable the separation of mixtures by:
(i) simple distillation,
(ii) paper chromatography;
(iii) fractional distillation.
(b) Give a reason for each of the following practices during titration in the laboratory.
(i) White tile is placed under the conical flask.
(ii) Burette readings are always recorded to two decimal places.
(iii) Calculate the volume of 2.5 moldm\(^{-3}\) stock HČI required to prepare 500 cm\(^3\) of 0.20 moldm HCI.
(a)(i) Wide difference in boiling points of components (for miscible liquids)/ difference in physical state (for liquid - solid solution)
(ii) Difference in absorption/retention rate of components
(ii) Close difference in boiling points of components.
(b)(i) To make the endpoint colour change colour easily visible/ in order not to overshoot the endpoint.
(ii) To ensure (high) accuracy of the titre value
(iii) Using Dilution formula
M\(_1\)V\(_1\) = M\(_2\)V\(_2\)
M\(_1\) = 2.5, V\(_1\) = ?, M\(_2\) = 0.20, V\(_2\) = 500
\(\frac{M_1V_1}{M_1}\) = \(\frac{M_2V_2}{M_1}\)
Make V\(_1\) the subject
V\(_1\) = \(\frac{M_2V_2}{m_1}\)
= \(\frac{0.20 \times 500}{2.5}\)
= 40.0 cm\(^3\)
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