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The relative atomic mass of magnesium

Weigh a magnesium ribbon, collect the hydrogen it makes and calculate Ar(Mg).

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What you do

1. Add the weighed magnesium ribbon to the acid. Note its mass.
2. Wait until all the magnesium has reacted (×5). Read the volume of hydrogen.
3. Calculate: n(H₂) = V ÷ 24 000 mL/mol = n(Mg); Ar = m ÷ n. Check your answer in the observations.
4. Calculate Ar(Mg) = m ÷ (V ÷ 24 000) from your mass and volume.

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