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]#?

1 Answer
Aug 16, 2017

Answer:

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#