861 past contests
Topic 14 · Riddle: iridium, named for the rainbow
Topic 5 · Riddle: hexanal, a straight-chain aldehyde
Topic 14 · Riddle: silicon carbide (carborundum)
Topic 4 · The anomalous temperature of maximum water density
Topic 4 · Converting ppm to percentage concentration
Topic 20 · Molarity of a dissolved hydrated salt
Topic 11 · Ideal gas volume from moles, temperature and pressure
Topic 1 · Remaining mass after a whole number of half-lives
Topic 10 · Enthalpy change from a mass of fuel and molar combustion enthalpy
Topic 1 · Mass of precipitate from a limiting-reagent double displacement
Topic 10 · Enthalpy of combustion from enthalpies of formation
Topic 3 · Ph of a saturated sparingly-soluble metal hydroxide
Topic 20 · Density of a solution from container mass measurements
Topic 20 · Mass of a hydrated salt from molarity and volume
Topic 19 · Empirical formula from percentage composition
Topic 19 · Percentage yield and mass obtainable at a given yield
Topic 36 · Cement chemistry: source of calcium in clinker
Topic 27 · Riddle: the mass spectrometer
Topic 39 · Direction of electron flow in a voltaic cell's external circuit
Topic 39 · Constructing a balanced voltaic cell equation from two half-cells