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Formulae, Equations and Amounts of Substance

Equations, concentration and reacting quantities

  • 3 things to know
  • Papers 1, 2 and 3

Overview

State symbols, ionic equations and spectator ions, n = c × V and converting cm³ to dm³, the amount of gas from molar volume, reacting masses and reacting gas volumes from a balanced equation, converting mol dm⁻³ to g dm⁻³, and the equivalence point and indicator colours in a titration.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

What do ionic equations show?

Numbers

State the formula for calculating the amount of gas in moles using molar volume.

Key term

State the four state symbols used in chemical equations and what each represents.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the four state symbols used in chemical equations and what each represents.

    Model answer

    (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solution.

  2. 2

    What do ionic equations show?

    Model answer

    Ionic equations show only the species that undergo chemical change, omitting spectator ions.

  3. 3

    Define spectator ions.

    Model answer

    Spectator ions are ions present in solution that do not participate in the reaction.

  4. 4

    State the formula relating amount of substance to concentration and volume of a solution.

    Model answer

    n = c × V, where n is amount in moles, c is concentration in mol dm⁻³, and V is volume in dm³.

  5. 5

    Calculate the amount of substance when concentration = 1.45 mol dm⁻³, volume = 0.7 dm³.

    Model answer

    Amount of substance = 1.45 × 0.7 = 1.02 mol.

  6. 6

    How do you convert a volume from cm³ to dm³?

    Model answer

    Divide the volume in cm³ by 1000.

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AAtomisation turns each element into gaseous atoms.
BIonisation energy removes electrons from the metal atoms.
CElectron affinity adds electrons to the non-metal atoms.

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Anode means electrode where oxidation occurs.
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