Numbers
AQA GCSE Combined Science Chemistry 8464
Atomic Structure and the Periodic Table
Topic overviewAtoms, elements and compoundsWord equations, symbols and balanced equationsMixturesFrom the plum pudding model to the nuclear modelBohr, Chadwick and the modern model of the atomRelative electrical charges of subatomic particlesSize and mass of atomsRelative atomic mass and electronic structureThe periodic tableDevelopment of the periodic tableMetals and non-metalsGroup 0Group 1Group 7
Bonding, Structure, and the Properties of Matter
Topic overviewChemical bonds, including metallic bondingIonic bondingIonic compoundsCovalent bonding and how it is representedThe three states of matter and changes of statePredicting state, state symbols, and the limits of the particle modelProperties of ionic compoundsProperties of small moleculesPolymers and giant covalent structuresProperties of metals and alloys, and why metals conductDiamond and graphiteGraphene and fullerenes
Chemical Analysis
Chemical Changes
Topic overviewThe reactivity seriesMetal oxides, extraction, and redox in terms of electronsAcids reacting with metals, neutralisation and saltsSoluble saltsThe pH scale and neutralisationThe process of electrolysis, and molten ionic compoundsUsing electrolysis to extract metalsElectrolysis of aqueous solutions
Chemistry of the Atmosphere
Topic overviewThe Earth's early atmosphereHow oxygen increased and carbon dioxide decreasedThe gases in today's atmosphere, and which are greenhouse gasesHuman activities which contribute to an increase in greenhouse gases in the atmosphereGlobal climate change and carbon footprintsAtmospheric pollutants from fuels, and their effects
Energy Changes
Organic Chemistry
Quantitative Chemistry
The Rate and Extent of Chemical Change
Quantitative Chemistry
Relative formula mass and concentration of solutions
- 3 things to know
- Chemistry Paper 1
Overview
Defining and calculating relative formula mass, showing both sides of a balanced equation total the same, percentage by mass of an element, and concentration in g/dm³ from the mass of solute and the volume of solution.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Calculate the percentage by mass of oxygen in CO₂, given relative atomic masses C = 12 and O = 16.
Numbers
Calculate the percentage by mass of nitrogen in NH₄NO₃, given relative atomic masses N = 14, H = 1 and O = 16.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define the relative formula mass of a compound.
Model answer
It is the sum of the relative atomic masses of all the atoms shown in the formula of the compound.
- 2
Calculate the relative formula mass of CO₂, given relative atomic masses C = 12 and O = 16.
Model answer
44.
- 3
Calculate the relative formula mass of H₂SO₄, given relative atomic masses H = 1, S = 32 and O = 16.
Model answer
98.
- 4
How does the total of the relative formula masses of the reactants compare with that of the products in a balanced equation?
Model answer
They are equal, provided each formula is counted the number of times shown by its balancing number.
- 5
For 2H₂ + O₂ → 2H₂O, show that the totals of relative formula mass are the same on both sides, given H = 1 and O = 16.
Model answer
The reactants total 2 × 2 + 32 = 36 and the products total 2 × 18 = 36, so both sides come to 36.
- 6
How is the percentage by mass of an element in a compound calculated?
Model answer
Divide the total relative atomic mass of that element in the formula by the relative formula mass of the compound, then multiply by 100.
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