Melting Point Determinations

RESULTS

Complete the Table below; remember to report the range.

Table

Compound

Fast mp

Slow mp

Lit. mp

2-methoxybenzoic acid

° C

° C

° C

urea

° C

° C

° C

benzamide

° C

° C

° C

urea/benzamide mixture

° C

° C

-----

4-nitrobenzaldehyde

° C

° C

° C

4-nitrobenzamide

° C

° C

° C

4-nitrobenzoic acid

° C

° C

° C

unknown

° C

° C

-----

Known #1

° C

° C

° C

Known #2

° C

° C

° C

Known #3

° C

° C

° C

Mixed mp #1

° C

° C

-----

Mixed mp #2

° C

° C

-----

Mixed mp #3

° C

° C

-----

 

Known #1: Code Number of Unknown Sample:

Known #2: Identity of Unknown:

Known #3:

 

 

DISCUSSION

Describe the process of melting in general. What is happening on a molecular level? Why? What is the relationship between mp and purity? Why is this so? Why do some compounds melt higher than others?

Describe the process of melting on a practical level. What did you see?

Compare your fast and slow mps. Were the values for the mp different? Why or why not? Why was the higher one higher? Which one was more accurate, closer to the actual or literature value? Why?

Describe the mixed mp experiment. Was the value for the mixed sample lower or higher than the two pure compounds? Why? Does the degree of difference imply anything about the purity of the compound?

Compare the mps of the nitro compounds. Compare the structures of the nitro compounds. Why in particular are the mps different?

Describe the thought processes you went through in identifying your unknown. Given your first mp determination, which compounds did you narrow your choices down to? Which compounds did you request from the TA? What did you learn from the mixed melting points? What is the identity of your unknown?