A jeweller makes a ring from pure silver, Ag.
The Avogadro constant is 6.02 × 10²³.
State what is meant by one mole of a substance.
The silver ring has a mass of 5.40 g.
Relative atomic mass (Ar): Ag = 107.9
Calculate the amount of silver in the ring in moles.
Give your answer to 3 significant figures.
Amount of silver = ...... mol
Calculate the number of silver atoms in the ring.
Give your answer in standard form to 3 significant figures.
The jeweller cleans the ring with water.
Relative atomic mass (Ar): H = 1.0, O = 16.0
Calculate the mass of one molecule of water, H₂O.
Give your answer in standard form to 3 significant figures.
Mass of one molecule = ...... g
A student says:
"One mole of hydrogen gas, H₂, contains the same number of atoms as one mole of helium gas, He."
Evaluate the student's statement.
55 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.