CAIE A Level Chemistry 9701 · Chemical energetics
The table shows the enthalpies of hydration and ionic radii for three ions.
| Ion | Ionic radius / pm | / kJ mol |
|---|---|---|
| Na | 102 | –406 |
| Mg | 72 | –1920 |
| Al | 53 | –4660 |
Compare the enthalpies of hydration of these three ions. Explain the factors that influence the magnitude of the enthalpy of hydration.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
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