12 g of commercial zinc is made to react with excess dilute H2SO4 .The total volume of hydrogen gas liberated was found to be 4.2 litres at 520 mmHg pressure and 279 K. Determine the percentage purity of the zinc.

The data below were determined for the reaction shown below. s2o82– + 3i – (aq) → 2so42– + i3– expt. # [s2o82–] (m) [i –] (m) initial rate 1 0.038 0.060 1.4 × 10 – 5 m/s 2 0.076 0.060 2.8 × 10 – 5 m/s 3 0.076 0.030 1.4 × 10 – 5 m/s the rate law for this reaction must be: