1. Why is it a disadvantage to use a large amount of sample on the hot stage? 2.

Question

1. Why is it a disadvantage to use a large amount of sample on the hot stage?

2. What effect do impurities in an organic solid have on melting point?

Questions 3 and 4 follow from question 2. There are many compounds with a melting point of 122-123degrees celsious. To test whether an unkown with melting point 122-123 is benzoic acid, a small amount of unknown is ground with a small amount of pure benzoic acid, and the melting point of this mixture is measured (the technique of mixed melting points).

3. What would you expect for the melting point if the unknown sample is benzoic acid?

4. What would you expect for the melting point if the unknown sample is another compound with melting point 122degrees celsius? Explain.

Explanation / Answer

1. hot stage results in decomposition of the samples. so it is avoided

2. presence of impurities will decrease the melting point of the pure compound.

3. it the unknown is benzoic acid, you wil get sharp melting point at 122-123

4. if the unknown is not benzoic acid, you wont get sharp melting pointt. you wil get broad melting point

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.