HSC Chemistry Paper 2026 Solutions and Explanations

To determine the molar mass of a compound, start by adding the atomic masses of each element in the molecule. For example, for water (H2O), the atomic mass of hydrogen (H) is approximately 1 g/mol, and oxygen (O) is about 16 g/mol. Therefore, the molar mass of water is 18 g/mol (2 × 1 + 16).

When balancing chemical reactions, ensure that the number of atoms of each element is the same on both sides of the equation. For example, in the reaction between hydrogen and oxygen to form water, 2H2 + O2 → 2H2O ensures that there are 4 hydrogen atoms and 2 oxygen atoms on each side of the equation.

For stoichiometry problems, use the mole ratio from the balanced equation to convert between reactants and products. If the problem provides the amount of one reactant, you can calculate the amount of products or other reactants by applying this ratio. This method is essential for solving quantitative problems in chemical reactions.