Question

How does `"silver bromide"` react with `"sodium thiosulfate"`? What mass of sodium thiosulfate is required to react with a `0.22*g` mass of `"silver bromide"` to give the complex ion `Na_3[Ag(S_2O_3)_2]`?

Answer 1

We assess the reaction:

`AgBr(s)uarr + 2Na_2S_2O_3(aq) rarr Na_3[Ag(S_2O_3)_2](aq) + NaBr(aq)`

Explanation:

This is a complexation reaction, and is still used in black and white photography.

And clearly, given the stoichiometric reaction, there is `1:2` stoichiometric equivalence between moles of `"silver bromide"`, and moles of `"sodium thiosulfate"`, and `1:1` stoichiometric equivalence between moles of `"silver bromide"`, and moles of `"silver(I) thiosulfate anion"`.

`"Moles of silver bromide"=(0.22*g)/(187.77*g*mol^-1)=1.17xx10^-3*mol`.

Clearly there is a `1.17xx10^-3*mol` quantity of `Na_3[Ag(S_2O_3)_2]`.

And this represents a mass of .......................... `1.17xx10^-3*molxx401.11*g*mol^-1~=0.50*g`