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Explain what is observed in the following.
An electrolyte ( ) is added to a colloidal solution of arsenious sulphide ( ).
An electrolyte ($\text{AlCl}_3$) is added to a colloidal solution of arsenious sulphide ($\text{As}_2\text{S}_3$).
Answer
Answer
AICoagulation (precipitation) of the sol occurs: the negatively charged $\mathrm{As_2S_3}$ sol is neutralised by the $\mathrm{Al^{3+}}$ ions and settles.
From ISC 2020 Chemistry Paper 1, question 12(iii).