Calculate the mass of hydrogen contained in 27 g of phosphoric acid.

The formula of phosphoric acid is Н3РО4.

In order to find how many grams of hydrogen is contained in 27 grams of this acid, you first need to find its relative molecular weight – Mr. It is calculated as the sum of the masses of all the atoms that make up the molecule.

Mr (Н3РО4) = 1 * 3 + 31 + 16 * 4 = 98, hence, the mass of one mole of acid is 98 grams.

We make the proportion:

98 g of Н3РО4 contains 3 g of H, while 27 g of Н3РО4 contains x g of H.

98/27 = 3 / x, hence x = 27 * 3/98, x = 0.83 g.

The mass of hydrogen is 0.83 g.