Mass of potassium dichromate (K₂Cr₂O₇) is 294 g, which is a 100%.
Given mass of chromium is 52 g. So, the mass percent of chromium in the compound is 17.687%: 52 g : x% = 294 g : 100% x = 52 ÷ 294 × 100 % x = 17.687%
Given mass of potassium is 39 g. <span>So, the mass percent of potassium in the compound is 13.265%: 39 g : x% = 294 g : 100% x = </span>39 ÷ <span>294 × 100 % x = 13.265%
Therefore, </span>the mass percent of oxygen in the compound is <span>69.048%: 100% - </span>17.687% - <span>13.265% = 69.048%.</span>
