Stoichiometry — IGCSE Physical Science (0652) questions by topic
Stoichiometry questions ask candidates to identify the missing substance in an incomplete equation, such as ammonia reacting with oxygen, calculate the mass of aluminium produced from a given mass of aluminium oxide, and find which substances share a given relative molecular mass. Identify, state and calculate are the command words, with calculate meaning working through defined steps using given relative atomic masses.
This page holds 6 real questions from 2023 papers, worth 1 to 5 marks. Because a stoichiometry calculation depends on using the correct term at each step, submitting your working for instant marking is the fastest way to catch a slip such as writing rusting instead of corroding before it affects how a whole calculation is read.
What examiners look for
- Examiners repeatedly report candidates using the word rusting in their answer.
- The term expected by the mark scheme was corroding, not rusting, according to the reports.
October–November 2023, Paper 21
Ammonia reacts with oxygen to produce substance X and water. An incomplete equation is shown. 4NH₃ + 5O₂ → X + 6H₂O What is the formula of X? A N₂ B NO C NO₂ D N₂O
Answer this question and get it marked →The formulae of three substances are shown. 1 NO₂ 2 C₂H₅OH 3 C₃H₈ Which substances have a relative molecular mass of 46? A 1, 2 and 3 B 1 and 2 only C 1 only D 2 only
Answer this question and get it marked →October–November 2023, Paper 22
Ammonia reacts with oxygen to produce substance X and water. An incomplete equation is shown. 4NH₃ + 5O₂ → X + 6H₂O What is the formula of X? A N₂ B NO C NO₂ D N₂O
Answer this question and get it marked →The formulae of three substances are shown. 1 NO₂ 2 C₂H₅OH 3 C₃H₈ Which substances have a relative molecular mass of 46? A 1, 2 and 3 B 1 and 2 only C 1 only D 2 only
Answer this question and get it marked →October–November 2023, Paper 41
Aluminium, Al, is obtained from aluminium oxide, Al2O3. The equation is: 2Al2O3 → 4Al + 3O2. Calculate the mass of Al produced from 204 tonnes of Al2O3. [Ar: Al, 27; O, 16; 1…
Answer this question and get it marked →October–November 2023, Paper 42
Aluminium, Al, is obtained from aluminium oxide, Al2O3. The equation is: 2Al2O3 → 4Al + 3O2. Calculate the mass of Al produced from 204 tonnes of Al2O3. [Ar: Al, 27; O, 16; 1…
Answer this question and get it marked →