In which state of matter – solid, liquid or gas – do the particles move around fastest? State Boyle's law - Leaving Cert Chemistry - Question b - 2014

Boyle's law states that for a definite mass of gas at constant temperature, the pressure is inversely proportional to the volume. Mathematically, this can be expressed as:

$P_1 V_1 = P_2 V_2$

(i) To find the number of moles, we use the formula:

$n = \frac{V}{V_{m}}$

where $V = 11.2$ litres and $V_{m} = 22.4$ litres/mol.

Thus, $n = \frac{11.2}{22.4} = 0.5 \text{ mol}$

(ii) To find the number of molecules, we can use Avogadro's number ($6 \times 10^{23} \text{ molecules/mol}$):

$\text{Number of molecules} = n \times \text{Avogadro's Number} = 0.5 \times 6 \times 10^{23} = 3 \times 10^{23} \text{ molecules}$

The process is called diffusion. It occurs when the gases diffuse through the air, and the resulting reaction forms the white ring of ammonium chloride.