L04 · 3.1.2.1, 3.1.2.2
Moles, particles and relative masses
Oxford Chemistry A Level · Ch 2.1 Relative atomic and molecular masses, the Avogadro constant, and the mole
3 marksCore chemistry3.1.2.1, 3.1.2.2
A cylinder contains 0.500 mol of carbon dioxide. The Avogadro constant
L=6.022×1023 mol−1.(a)Calculate the mass of carbon dioxide in the cylinder.
[1 mark] (b)Calculate the number of molecules in the cylinder.
[1 mark] (c)Calculate the total number of atoms in the cylinder.
[1 mark] 3 marksCore chemistry3.1.2.1, 3.1.2.2
Relative masses are measured on the carbon-12 scale.
(a)Define the term relative atomic mass.
[2 marks] (b)Hydrated copper(II) sulfate is
CuSO4⋅5H2O. Calculate its relative formula mass.
3 marksCore chemistry3.1.2.1, 3.1.2.2
A student dissolves 5.00 g of calcium chloride,
CaCl2, in water. The Avogadro constant
L=6.022×1023 mol−1.(a)Calculate the amount, in moles, of
CaCl2. (b)Calculate the number of chloride ions in the solution.
[2 marks] 4 marksUnfamiliar context3.1.2.1, 3.1.2.2
Caffeine has the molecular formula
C8H10N4O2. A cup of coffee contains about 90 mg of it. The Avogadro constant
L=6.022×1023 mol−1.(a)Calculate the mass, in kg, of one caffeine molecule.
[2 marks] (b)Calculate the number of nitrogen atoms in 1.00 mg of caffeine.
[2 marks] 4 marksUnfamiliar context3.1.2.1, 3.1.2.2
A jeweller plates a ring with 2.50 mg of silver. The Avogadro constant
L=6.022×1023 mol−1.(a)Calculate the number of silver atoms in the plating.
[2 marks] (b)Without a full calculation, explain which contains more atoms: 1.00 g of helium or 1.00 g of carbon.
[2 marks] 