CAIE IGCSE Chemistry Reacting Masses Volumes and Concentrations

Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise multi-step stoichiometry by converting the given quantity to moles, applying an equation ratio and converting to the requested mass, volume or concentration.

How this is tested

convert the given mass, gas volume or solution data into moles with consistent units
use coefficients from the balanced equation to obtain the required mole quantity
identify the limiting reactant or excess, then calculate mass, gas volume or concentration

[Maximum number: 3]

The symbol equation for the industrial production of ammonia is shown.

\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g}) \quad \Delta H=-90 \mathrm{~kJ} / \mathrm{mol}

An incomplete symbol equation for the preparation of ammonia in the laboratory is shown.

\mathrm{CaO}+2 \mathrm{NH}_{4} \mathrm{Cl} \rightarrow \mathrm{CaCl}_{2}+\ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots . .+2 \mathrm{NH}_{3}

Calculate the volume of ammonia, $\mathrm{NH}_{3}$ , measured at room temperature and pressure, which forms when 1.12 g of CaO is heated with excess $\mathrm{NH}_{4} \mathrm{Cl}$ .
$\left[M_{r}: \mathrm{CaO}, 56\right]$

How this is tested

Question 3(f)(iii)