Page 37 - Curriculum Visions Dynamic Book

alloy: a mixture of a metal and various other elements.
electrolysis: an electrical–chemical process that uses an electric
current to cause the break up of a compound and the movement of metal ions in a solution. The process happens in many natural situations (as for example in rusting) and is
also commonly used in industry for purifying (refining) metals or for plating metal objects with a fine, even metal coating.
electroplating: depositing a thin layer of a metal onto the surface of another substance using electrolysis.
 Chromium was used as a decorative finish in many of the world’s older classic cars. This is because, at the time, no other corrosion-resistant finish was available. Modern bumpers are not made of iron, but of polycarbonate, and so do not need to be chromium protected at all.
Preparation of chromic acid
Chromic acid is prepared by stirring brown chromic oxide in water.
The resulting acid is very corrosive and is used for cleaning glassware. It is also a strong oxidising agent.
Brown chromic oxide is added to water.
Chromic acid
Brown chromic oxide
EQUATION: Laboratory production of chromic acid
Chromic oxide + water ➪ chromic acid CrO3(s) + H2O(l) ➪ H2CrO4(aq)
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