The energy involved in change of state

1 mark · Normal

Why is it important to use a water bath instead of a direct flame when heating substances like naphthalene to study their change of state?

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To prevent naphthalene (which is flammable) from catching fire and to allow gentle, even heating.

Must show: reduce fire risk, gentle/even heating

Also accept: Avoids overheating the sample

Common mistakes: Saying only 'to heat it up'

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Marking points

B1 · 1 mark · Explains preventing fire/flammability or allows more even heating.

Worked solution

Naphthalene is flammable and could catch fire if heated directly. A water bath heats it safely and evenly, reducing this risk.