Question

How do you calculate the relative formula mass of copper oxide using the periodic table?

Answer 1

The relative formula mass is calculated by adding the relative atomic masses of the atom multiplied by the number of atoms present in the chemical formula. The value of relative atomic masses can be obtained from the periodic table.

Complete step by step answer:
The relative atomic mass of the element is defined as the relative mass of the atom compared to the mass of carbon 12 atom. The relative atomic mass is denoted by ${A_r}$.
The value of relative atomic mass is given in the periodic table
The relative formula mass is the sum of the relative atomic masses of the atom multiplied by the number of atoms shown in the formula. The relative formula mass is denoted by ${M_r}$.
The given compound is copper oxide. The copper oxide is in two forms copper (I)oxide and copper (II)oxide. The molecular formula of copper (I) oxide is $C{u_2}O$ and the molecular formula of copper (II)oxide is CuO.
The relative atomic mass of Cu is 63.55 amu.
The relative atomic mass of O is 16.00 amu
The relative formula mass of $C{u_2}O$is calculated as shown below.
$\Rightarrow (63.55 \times 2) + 16.00$
$\Rightarrow 143.10amu$
The relative formula mass of CuO is calculated as shown below.
$\Rightarrow 63.55 + 16.00$
$\Rightarrow 79.55amu$
Therefore, the relative formula mass of copper (I)oxide $C{u_2}O$is 143.10 amu and the relative formula mass of copper (II) oxide is 79.55 amu.

Note:
The relative atomic mass has no units. The calculation of relative formula mass is done the same as the calculation of molecular weight where atomic mass of the atoms are added but the unit of molecular weight is g/mol.