Question 1

3 Which of the following compounds would be likely to evaporate readily? Explain your answer.

Accepted Answer

Only (b) and (c). Fenchone will evaporate readily because it is spherically shaped. Pentacene will evaporate becaue it is cylindricaly shaped. Hexadecane has a zig-zag shape and strong van der Waal attractions.

Question 2

Which of the following compounds could be subjected to sublimation at atmospheric pres- sure?
a) Compound A: vapor pressure at its melting point = 770 mm Hg
(b) Compound B: vapor pressure at its melting point = 400 mm Hg
(c) Compound C: vapor pressure at its melting point = 10 mm Hg

Accepted Answer

Compounds A and B will have significant vapor pressure at their melting point.

Question 3

You have a mixture of p-nitrobenzaldehyde (vapor pressure 0.01 at its melting point of 106˚) and camphor. Explain how you would separate these two compounds by sublimation. How would you perform the sublimation if benzoic acid instead of camphor is used?

Accepted Answer

Subject the mixture of p-nitrobenzaldehyde and camphor to atmospheric sublimation; the camphor will sublime onto the tube filled with ice while the p-nitrobenzaldehyde remains in the flask itself. If benzoic acid is used, the mixture could be separated similarly using vacuum sublimation.

Question 4

In the preceding problem, which compounds could be vacuum sublimated?

Accepted Answer

Only compund C. The others wou

3 Which of the following compounds would be likely to evaporate readily? Explain your answer.

Which of the following compounds could be subjected to sublimation at atmospheric pres- sure? a) Compound A: vapor pressure at its melting point = 770 mm Hg (b) Compound B: vapor pressure at its melting point = 400 mm Hg (c) Compound C: vapor pressure at its melting point = 10 mm Hg

You have a mixture of p-nitrobenzaldehyde (vapor pressure 0.01 at its melting point of 106˚) and camphor. Explain how you would separate these two compounds by sublimation. How would you perform the sublimation if benzoic acid instead of camphor is used?

In the preceding problem, which compounds could be vacuum sublimated?

Introduction to the Organic Laboratory

Crystallization

Melting Points

Extraction

Drying Organic Solutions

Simple Distillation

Fractional Distillation

Vacuum Distillation

Steam Distillation

Refractive Index

Column Chromatography

Thin Layer Chromatography

Gas Chromatography

Carrying Out Typical Reactions

Infrared Spectroscopy

Proton Nuclear Magnetic Resonance Spectroscopy

The Chemical Literature

Filters

Exam 10: Sublimation

3 Which of the following compounds would be likely to evaporate readily? Explain your answer.

Which of the following compounds could be subjected to sublimation at atmospheric pres- sure? a) Compound A: vapor pressure at its melting point = 770 mm Hg (b) Compound B: vapor pressure at its melting point = 400 mm Hg (c) Compound C: vapor pressure at its melting point = 10 mm Hg

You have a mixture of p-nitrobenzaldehyde (vapor pressure 0.01 at its melting point of 106˚) and camphor. Explain how you would separate these two compounds by sublimation. How would you perform the sublimation if benzoic acid instead of camphor is used?

In the preceding problem, which compounds could be vacuum sublimated?

Introduction to the Organic Laboratory

Crystallization

Melting Points

Extraction

Drying Organic Solutions

Simple Distillation

Fractional Distillation

Vacuum Distillation

Steam Distillation

Refractive Index

Column Chromatography

Thin Layer Chromatography

Gas Chromatography

Carrying Out Typical Reactions

Infrared Spectroscopy

Proton Nuclear Magnetic Resonance Spectroscopy

The Chemical Literature

Filters