Calculate the relative molecules of the mass of substances: 1) CuO 2) CH4 3) HCI

Let us find the relative molecular mass of substances by adding up the relative atomic masses of the elements, having previously multiplied them by the indices at the elements. Relative molecular weight is measured in amu. e. m. (atomic mass unit).

Let’s calculate the relative molecular weights of copper (II) oxide, methane and hydrochloric acid.

1) Mr (CuO) = Ar (Cu) + Ar (O) = 63.5 + 16 = 79.5 a. eat.

2) Mr (CH4) = Ar (C) + 4 * Ar (H) = 12 + 4 * 1 = 16 amu. eat.

3) Mr (HCl) = Ar (H) + Ar (Cl) = 1 + 35.5 = 36.5 a. eat.