Why does one reactant usually run out before the other?
The reactant left over is the excess reactant.
Adding more magnesium would produce more hydrogen because magnesium is the limiting reactant.
Use the equation's mole ratio to identify which reactant is in short supply.
The reactants are rarely mixed in the exact equation ratio, so one usually runs out first.
Flashcards for AQA GCSE Chemistry 3.2.4 Limiting reactants (HT only), covering the key terms, definitions and equations you need to recall for Paper 1 and Paper 2. 21 cards, matched to the AQA GCSE Chemistry (8462) specification. Recall questions account for roughly 40% of marks at GCSE Chemistry, so these target the marks you can secure before the paper starts.
