Question

Composition	Melting Point Range (C)
Benzoic Acid (100%)	123 C
Maleic Acid (100%)	135 C
Benzoic:Maleic (75:25)	113-116 C
Benzoic:Maleic (50:50)	113-118 C
Benzoic:Maleic (25:75)	123-129 C

A) Summarize the data (melting point ranges of the 3 mixed samples)

B) What conclusions can be made about the effect of impurities on the melting point range?

C) How did you reach that conclusion?

Answer 1

Solution:

As we can see that pure sample has sharp melting point but if their is impurity then the melting point comes in a range. Similarly we can see here when we have 75% benzoic acid and 25% maleic acid and melting point is in the range 113-116 with difference of 3 degree and the range increases on increasing the concentration of maleic acid.

B) we have seen that on adding impurity the melting point comes in a range but on increasing the concentration of impurity with higher melting point and which can strengthen the inter molecular force, the melting range even becomes broad and melting point increases.

C) genreally the melting point decreases on adding the impurity because of disturbance in the lattice but here maleic alei acid have two carboxlica acid group which can form hydrogen bonding with the benzoic acid and can hold the molecules together soso melti point increases as well as the range on increasing concentrations of maleic acid.