A student planned an experiment to determine the empirical formula of magnesium oxide by heating magnesium and recording the resulting change in mass.
Some of the equipment the student used is shown in the diagram below.
Suggest another piece of equipment that would be essential to find the empirical formula of magnesium oxide.
The method the student used is shown below.
Step 1 | Measure the mass of the crucible together with its lid |
Step 2 | Coil a 10 cm strip of magnesium ribbon and place into the crucible |
Step 3 | Reweigh the crucible and lid |
Step 4 | Heat the crucible strongly using the apparatus in the diagram in part (a) |
Step 5 | Use the tongs to lift the crucible lid slightly during heating |
Step 6 | As it nears completion, place the crucible on a heat-proof mat and heat strongly for a further 5 minutes |
Step 7 | Allow the crucible to cool and reweigh the crucible and lid |
The student obtained the following results.
Mass of crucible and lid / g | 25.68 |
Mass of magnesium, crucible and lid / g | 27.01 |
Mass of magnesium oxide, crucible and lid / g | 27.81 |
Using the results in the table above, deduce the empirical formula of magnesium oxide.
Another student performed the same experiment but tapped the residue with tongs to break it up during Step 6.
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