Question

How many moles of mercury(II) oxide, HgO, are needed to pro- duce 125 g of oxygen, O2?

Answer 1

Write out the balanced equation:

2HgO ----> 2Hg + O2

Convert grams of O2 to moles:

(125g of O2 * 1 mole)/ 32g of O2 = 3.91

Look at the ratio with HgO to O2:

2:1

Therefore:

3.91 * 2 = 7.82