Answer to Question #231082 in General Chemistry for Iman

Question

volume of distilled water needed to add to 50 cm³ of 0.2 mol dm³ sodium thiosulphate solution, Na2S2O; so that a 0.025 mol dm² sodium thiosulphate solution, Na2S₂O3 is produced.

Answer 1

Let V mL of 0.025M sodium formate solution should be added to 50ml of 0.2M formic acid to produce a buffer solution of Na2S₂O3

pH=pKa+log $\frac{[HCOOH]}{ [HCOONa]}$

​ pka of Na2S₂O3 = 1.72

= pH of Na2S₂O3 = 9

= 31.72 ml