A student performing this experiment weights out 0.6680 grams of an antacid tablet. It is was determined that this tablet contained 0.4210 grams of CaCO3. What is the percent CaCO3 of this tablet?

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: