Question

At what point should you start recording the melting point of a compound? (a) when the sample starts to collapse; (b) when the entire sample turns completely into a liquid; (c) when the first drop of liquid forms.

Answer 1

Option C is correct one.Explanation given below.

Determining the melting point of a compound is one way to test if the substance is pure. A pure substance generally has a melting range (the difference between the temperature where the sample starts to melt and the temperature where melting is complete) of one or two degrees. Impurities tend to depress and broaden the melting range so the purified sample should have a higher and smaller melting range than the original, impure sample.