← Chemistry syllabus

SingaporeChemistry

Stoichiometry and the Mole Concept

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are chemical formulae built from ionic charges, and how is a chemical equation balanced?

Write formulae of ionic compounds from the charges on their ions, construct and balance chemical equations, and add state symbols
A focused answer to the O-Level Chemistry outcome on formulae and equations. Building ionic formulae by balancing charges, balancing chemical equations atom by atom, and adding the correct state symbols.
8 min answer →

How is the concentration of a solution defined, and how does a titration find an unknown concentration?

Define concentration in mol per dm cubed and g per dm cubed, interconvert the two, and carry out titration calculations to find an unknown concentration
A focused answer to the O-Level Chemistry outcome on concentration and titration. Concentration in mol per dm cubed and g per dm cubed, converting between them, and the standard three-step titration calculation.
9 min answer →

How do balanced equations let chemists calculate reacting masses, gas volumes and percentage yield?

Use mole ratios from balanced equations to calculate reacting masses and gas volumes, identify the limiting reagent, and calculate percentage yield
A focused answer to the O-Level Chemistry outcome on reacting-mass calculations. Using mole ratios from balanced equations to find masses and gas volumes, identifying the limiting reagent, and calculating percentage yield.
9 min answer →

How do chemists count atoms by weighing, using relative masses and the mole?

Define relative atomic and molecular mass, the mole and the Avogadro constant, and interconvert mass, amount in moles and number of particles
A focused answer to the O-Level Chemistry outcome on the mole. Relative atomic and molecular mass, the mole and the Avogadro constant, and converting between mass, amount in moles and number of particles.
8 min answer →