of~an~element} = \frac{mass~of~an~element~in~the~compound}{relative~formula~mass~M_r} \times 100\) There are six atoms of hydrogen in the compound, so the mass of hydrogen is 6 × 1 = 6.

The solid copper hydroxide precipitate was collected by filtering, washed with water and dried in an oven. It was found to weigh 1.95g and from this we can calculate the mass of copper sulfate in ...