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4.3 Quantitative chemistry

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do we convert between mass, moles and number of particles?

Amounts of substance in equations; calculating moles from mass; using moles to balance equations and find masses; the mole calculation triangle.
A focused answer to AQA GCSE Chemistry 4.3.2, covering how to convert between mass, moles and number of particles, using the moles equation, and using mole ratios from balanced equations to deduce amounts.
9 min answer →

How do we measure and calculate the concentration of a solution?

Concentration of solutions in g/dm3 and mol/dm3; converting between them; using concentration in calculations; and titration ideas.
A focused answer to AQA GCSE Chemistry 4.3.4, covering concentration in g/dm3 and mol/dm3, converting between mass, volume and concentration, and how concentration is used in titration calculations.
9 min answer →

Why is mass conserved in reactions, and what is the mole?

Conservation of mass and balanced symbol equations; relative formula mass; the mole and the Avogadro constant; apparent changes in mass in reactions involving gases.
A focused answer to AQA GCSE Chemistry 4.3.1 and 4.3.2, covering conservation of mass and balanced equations, relative formula mass, the mole and the Avogadro constant, and why mass can appear to change in reactions involving gases.
9 min answer →

How do we calculate the mass of a product from the mass of a reactant?

Reacting masses; using moles to calculate the mass of a product or reactant; limiting reactants; and deducing balanced equations from masses.
A focused answer to AQA GCSE Chemistry 4.3.2 and 4.3.3, covering how to calculate reacting masses using moles and mole ratios, the idea of a limiting reactant, and using masses to deduce the balancing numbers in an equation.
9 min answer →

How do we measure how efficient a reaction is?

Percentage yield; why yields are less than 100 percent; atom economy; and how both are used to judge how efficient and sustainable a reaction is.
A focused answer to AQA GCSE Chemistry 4.3.5 and 4.3.6, covering how to calculate percentage yield, why yields are below 100 percent, how to calculate atom economy, and how both measures judge the efficiency and sustainability of a reaction.
9 min answer →