Question

Determine the number of moles (of molecules or formula units) in the following sample.

36.4 g KNO3 .

Answer 1

Number of moles = 0.36 moles.

Step-by-step explanation:

Given the following data;

Mass of KNO3 = 36.4g

To find the number of moles;

`Number \; of \; moles = \frac {mass}{molar mass}` .....equation 1.

Molar mass of KNO3;

Molecular weight of potassium, K = 39g/mol.

Molecular weight of nitrogen, N = 14g/mol.

Molecular weight of oxygen, O3 = 16*3 = 48g/mol.

Therefore, molar mass of KNO3 = 39 + 14 + 48 = 101g/mol

Substituting the values into eqn 1, we have;

`Number \; of \; moles = \frac {36.4}{101}`

Number of moles = 0.36 moles.