Question

Calculate the mass of AgBr that can be dissolved in one liter of a 0.500 M solution of Na_2S_2O_3. K_sp(AgBr) = 5.0 times 10^-13 and K_f(Ag(S_2O_3)_2^3-) = 1.7 times 10^13.
Please help!!!!!!

Answer 1

The balanced chemical equation for the reaction is:

AgBr(s) + 2S2O3^-2(aq)-----------------------> Ag(S2O3)2 (aq) + Br^-(aq)

from the above equation we can understand that for every mole of AgBr to react requires 2 moles of S2O3^-2

0.5mol/liter* 1 liter= 0.5 mol Na2S2O3

0.5 mol Na2S2O3*1mol AgBr/2mol S2O3= 0.25 mols of AgBr that can react

Now we have to convert 0.25 moles of AgBr into grams.

= 0.25 moles x molecular mass of AgBr

= 0.25mol x 188 g /mol

= 47grams of AgBr will dissolve in 1litre of 0.5M sodium thiosulphate solution.