Sodium Thiosulfate (Na₂S₂O₃, Molar Mass = 158 $\rightarrow$ 2I^-(aq) + S₄O₆^2-(aq)
A) 100%
B) 48

Multiple Choice

Sodium thiosulfate (Na₂S₂O₃, molar mass = 158.2 g/mol) is used in the development of photographic film. Your summer job is at a photography lab and you need to check the purity of an outdated supply. You react 40.21 mL of 0.246 M iodine solution with a 3.232 g sample. What is the percent purity of the sodium thiosulfate that you report to your boss?
I₂(aq) + 2S₂O₃^2-(aq) $\rightarrow$ 2I^-(aq) + S₄O₆^2-(aq)

A) 100%
B) 48.4%
C) 96.8%
D) 98.6%
E) 84.4%