collecting purity of organic solid

What is the melting point like in an impure substance

It melts over a wide range of temp and lower temp than pure substance

What is the process of checking melting point

Place some solid in melting tube

Place in apparatus and heat slowly

Record start temp of melting and end temp

Repeat and find average

Compare values with data book

The greater the range - the more impure

How does the equipment look like when checking melting point

Capillary tue strapped to thermometer immersed in some heating oil

The heating oil must be Low flammability and have a higher boiling point than sample

Why is melting point not a good method for checking purity

Substances can have same melting point

Where should the thermometer be

The thermometer should be above level of the surface of boiling liquid