Alcohols, haloalkanes and analysis

Question 1

What is the functional group of alcohols

Answer 1

-OH

Question 2

Properties of alcohols compared to alkenes

Answer 2

Les volatile
Higher mp
Greater solubility

Question 3

Explain why alcohols have high mps

Answer 3

Contain an O-H bond that is polar due to the difference in electronegativity
Form strong hydrogen bonds with other molecules that take more energy to overcome

Question 4

Why do alcohols have a high solubility in water

Answer 4

They can form hydrogen bonds with water
as carbon chain increases, solubility decreases

Question 5

What is the difference between primary, secondary and tertiary alcohols

Answer 5

1* - OH group is attached to one alkyl group
2* - OH group is attached to two alkyl group
3* - OH group is attached to three alkyl group

Question 6

Method and result of 1* oxidation

Answer 6

1* alcohol is oxidised by acidified potassium dichromate
Orange solution will turn green
Fractional distillation for a aldehyde
Reflux for a carboxylic acid

Question 7

Method and result of 2* oxidation

Answer 7

Oxidised using acidified potassium dichromate
Heated under reflux to form a ketone

Question 8

What happens when a 3* is oxidised

Answer 8

Nothing, solution remains orange as 3* alcohols are too stable

Question 9

What is dehydration

Answer 9

When an alcohol is heated under reflux in the presence of H2SO4 to produce and alkene and water

Question 10

How are haloalkanes formed from alcohol

Answer 10

hydrogen halide + alcohol are heated under reflux with sulfuric acid

Question 11

What is a nucleophile

Answer 11

An electron pair donator

Question 12

What happens in the hydrolysis of a haloalkane

Answer 12

-OH group reacts with haloalkane to form alcohol and a halogen ion
The stronger the carbon-halogen bond the slower the reaction

Question 13

What experiment can you do to measure the rate of hydrolysis of a haloalkane

Answer 13

Carry out the reaction in the presence of AgNO3
Use H2O as the nucleophile as Haloalkanes are insoluble in water
Carry out reaction in presence of ethanol solvent
Ag reacts with halide to produce silver halide
The longer it takes precipitate to form, the higher the carbon-halogen bond enthalpy

Question 14

Why are CFCs harmful

Answer 14

CFCs are very stable, so they reside in the atmosphere for a long time
UV in the stratosphere causes a Cl radical to form that reacts with O3 to produce O2

Question 15

When was the Montreal protocol signed

Answer 15

1987

Question 16

How would you purify an organic product

Answer 16

Ensure tap of separating funnel is closed
Pour mixture into separating funnel
Allow layers to settle
Add water to see which layer increases in volume (this will be the aqueous layer)
Place a conical flask under separating funnel and open the stopper till all of the lower layer has been removed
Use another conical flask to collect the other layer

Question 17

How would you get from an alkene to alkane

Answer 17

H2 with Ni catalyst

Question 18

What does IR do to particles

Answer 18

Bonds absorb IR, making them bend, vibrate and stretch more

Question 19

What affects the amount a bond stretches or bends

Answer 19

Mass - heavier vibrate more
Strength - stronger bonds vibrate faster

Question 20

What happens with IR and atmospheric gases

Answer 20

H2O, CO2 and CH4 absorb longer wavelength IR and then re-emit this energy as radiation, increasing the temperature of the atmospher