Quantitative Chemistry, Energy & Reaction Types is one of 9 topics in the Grade 11 Physical Sciences CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. The coefficients in a balanced chemical equation represent:
The mole ratio in which substances react and are produced
The mass ratio in which substances react
The number of atoms in each individual molecule only
The temperature at which the reaction occurs
Answer: The mole ratio in which substances react and are produced — Balanced equation coefficients give the mole ratio of reactants to products, the basis of all stoichiometric calculations.
Easy
2. Which formula converts a given mass of a substance into moles?
n = m/M
n = M/m
n = m x M
n = m + M
Answer: n = m/M — The number of moles n is calculated as n = m/M, where m is mass and M is molar mass.
Medium
3. For the reaction 2Mg + O2 -> 2MgO, 12 g of magnesium (M=24 g/mol) reacts completely with excess oxygen. Calculate n(Mg), in moles, using n=m/M.
