Question

In order to record an accurate melting point, you need to heat the sample slowly. Give at least two reasons.

Answer 1

1)
If we heat the sample at a fast rate, whole of sample can melt at any time and we may not know the exact melting point as excess heat due to fast heating may raise the temperature of melted sample.
So recorded temperature can be more than the actual melting point.

2)
Other drawback of fast heating can be that whole of the substance will not melt.
It can so happen that some part of sample melt and its temperature starts incraesing while rest of the sample it still melting. This may also lead to wrong determination of melting point