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OCR Gateway B Module C5: How Much?

Note: you must be able to recall all formulas on this page, most questions will not give them and they are not at the front of the question paper

Molar mass:

Empirical formula:


Sodium and salt:



Measuring gas produced by a reaction:


Example: 2NO2 ⇌ N2O4:

The Contact process:


Electrolysis and conductivity:

Strength vs concentration:

Ionic lattices:

Precipitation reactions:

Preparing a sample of insoluble salt:

Spectator ions:

Ionic equations:

  • Lead nitrate (aq) + sodium iodide (aq) → lead iodide (g) + sodium nitrate (aq)
  • Pb(NO3)2 + 2NaI → PbI2 + 2NaNO3
  • Pb2+ + 2I- → PbI2
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