How can melting point determine purity?
In this regard, how do you determine the purity of a substance?
%purity= g of pure substance obtained ÷ g of given sample ×100. Percentage purity of a substance can be calculated by dividing the mass of the pure chemical by the total mass of the sample, and then multiplying this number by 100.
Secondly, can impurities increase melting point? The presence of impurities in a substance results in a lower melting point due to a process called melting point depression. Melting point depression is the reason why adding salt to frozen streets helps to melt the ice. Melting point depression occurs due to the nature of a material's solid state.
One may also ask, how do you determine the melting point of an unknown substance?
When determining the melting point of an unknown substance, it is a common practice to first determine a rough melting point by quickly heating the sample followed by a careful determination of the melting point by gradually heating the sample at the rate of 1-2 C /min.
What are the criteria for purity?
However for practical purpose in laboratory only melting point and boiling point are used as criteria for purity. A pure organic solid has a definite and sharp (sudden, rapid and complete) melting point, while an impure substance has a lower and indefinite melting point.