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(i) First test liquids obtained by melting substances. Melt the following substances, but heat
very gently and cautiously because otherwise they may ignite and burn: sulphur, wax,
naphthalene, polyethylene material, tin, lead and, if available, a low melting point salt such as
lead bromide, m.p. 488oC, or potassium iodide, m.p. 682oC . Test the conductivity of the melt
by dipping in the electrodes and waiting a few moments for the electrodes to reach the
same temperature. This ensures that the electrodes are in contact with the liquid and not
the solidified melt. Scrape and clean the electrodes between each test.
(ii) Test ethanol, or methylated spirits, acetone, carbon (IV) chloride, vinegar, sugar
solution, copper (II) sulphate solution, sodium chloride solution, and other substances
dissolved in water. Clean and dry the electrodes between each test.
(iii) Test pure distilled water for conductivity. Put the electrodes into a beaker of distilled
water. The bulb does not light up so pure water does not conduct electricity. Very gradually
stir small crystals of common salt into the water. Note any changes to the bulb as the salt
dissolves. Classify substances into the following groups: (a) those which conduct electricity
in the solid state and those which do not; (b) those which conduct in the liquid state and
those which do not; (c) those which conduct when dissolved in water and those which do not
sharon kalunda answered the question on April 12, 2019 at 08:18
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