A colloidal solution of AgI is prepared by two different methods as shown in figure below. 1. What is the charge of AgI colloidal particles in the two test tubes (A) and (B)? 2. Give reasons for the origin of charge.

1. Test tube (A) has negative charge whereas test tube (B) has positive charge on the colloidal particles. 2. In test tube (A), I^– is adsorbed on precipitate AgI [or AgI/I^– is formed] and in test tube (B), Ag^+ is adsorbed on precipitate AgI [or AgI/ Ag^+ is formed].

A colloidal solution of AgI is prepared by two different methods …

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Question

A colloidal solution of AgI is prepared by two different methods as shown in figure below.

What is the charge of AgI colloidal particles in the two test tubes $(A)$ and $(B)?$
Give reasons for the origin of charge.

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Answer

Test tube $(A)$ has negative charge whereas test tube $(B)$ has positive charge on the colloidal particles.
In test tube $(A), I^–$ is adsorbed on precipitate $AgI$ $[$or $AgI/I^–$ is formed] and in test tube $(B), Ag^+$ is adsorbed on precipitate $AgI$ $[$or $AgI/ Ag^+$ is formed$].$