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Questions
With the help of an appropriate example, justify that some of the chemical reactions are determined by a change in colour.
Give a chemical equation for the reaction involved in the above case.
Give one example of a chemical reaction characterised by a change in colour.
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Solution
When sulphur dioxide gas is passed through an acidified potassium dichromate solution, the orange colour of the potassium dichromate solution changes to green colour.
\[\ce{3SO2_{(g)} + K2Cr2O7_{(aq)} + H2SO4_{(aq)} -> K2SO4_{(aq)} + Cr2(SO4)3_{(aq)} + H2O_{(l)}}\]
Notes
Students should refer to the answer according to their questions.
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