Question

3.Arrange glycerol, ethanol, and ethylene glycol in order of increasing strength of intermolecular forces. While the dispersion force and the dipole moment steadily increase in this series, they do not do so at a rate that is sufficient to account for the exponential increase in boiling point. What accounts for the exponential increase in the boiling point in this series?

4.A liquid with high boiling point has a high evaporation rate. State True OR False

5.2-propanol has a lower boiling point than 1-propanol at 760 mm Hg. Why ?

6.It is safe to discard organic liquids in the sink after the experiment. State True OR False with a reason

Answer 1

Q. 3

The boiling point is corresponding to the intermolecular forces exist in the molecule. The strongest the intermolecular interactions higher will be the boiling point.

Ethylene has Vander wall interaction that is weakest of all hence ethylene has lowest boiling point.

Ethanol has -OH group that is capable to have dipole-dipole interaction because of O-H bond is polar. Followed by hydrogen bonding hence boiling point is higher than ethlene.

Because dipole-dipole interaction are stronger than Vanderwall interactions.

For ethlene glycol it has two alcohol groups OH it also has dipole-dipole interactions and due to presence of two -OH groups the number of hydrogen bonding exist per molecules of glycol is more than ethanol.

While glycerol has highest boiling point due to presence of dipole-dipole interactions and due to presence of three -OH bonds there are maximum hydrogen bonding present per molecules of glycerol

Boiling point order is

Glycerol> glycol > ethanol > ethlene.

Q. 4

FALSE

High boiling point means intermolecular forces are stronger hence these liquids do not leave the surface of liquid easily in order to vaporize. Hence the liquid with high boiling point vaporize less .

Q. 5

2-propanol and 1- propanol are both having polar bonds which leads to dipole-dipole interactions and hydrogen bonding . The difference in boiling points these compounds is due to the extent of hydrogen bonding.

1- propanol can have three hydrogen bonds possible , while 2-propanol have only two hydrogen bonds because one side is sterically hindered with carbon chain.

Hence 1-propanol has higher boiling point. Always branching decreases the boiling points. .

Q. 5

FALSE

To discard in sink is not safe. Organic compounds may be petroleum and they may produce toxic gases.