M4 Chapter 16 - Organic Synthesis

Question 1

Describe how a quickfit apparatus is connected.

Answer 1

Grease joints using petroleum on inside of joints before connecting the pieces together.

Question 2

In a distillation setup, why is it important to have a continuous water flow around the condenser?

Answer 2

So that the water remains cooled to allow the mixture to be distilled.

Question 3

Describe a method to separate immiscible liquids.

Answer 3

Pour water mixture into separating funnel and some distilled water.

Add stopper and invert flask to mix mixture.

Continue shaking until no whistle sound.

To collect water on lower layer, open stopper and place beaker under the spout.

Use another beaker to collect desired organic layer.

Shake liquid with drying agent.

Question 4

Name two drying agents.

Answer 4

Magnesium Sulphate
Calcium Chloride

Question 5

How to use drying agents?

Answer 5

Add selected drying agent to the organic product.

If the drying agent forms clumps, add more until they are moving freely.

Use gravity filtration to collect dry product.

Filtrate is the product.

Question 6

What does re-distillation mean?

Answer 6

When a liquid is purified by using multiple distillation.

Question 7

How can unsaturated hydrocarbon be tested?

Answer 7

Use bromine water

Add drops of bromine water to sample and mix

Positive = Orange to colourless

Question 8

What are reagents used to test haloalkanes and what are observations?

Answer 8

Reagents = Silver Nitrate, ethanol and water.

Observatons:
Chloro- = white precipitate
Bromo = cream precipitate
Iodo = yello precipitate

Question 9

What are the 3 reagents that can be used to test carbonyls?

Answer 9

Acidified Potassium Dichromate

Fehling’s Solution

Tollen’s Reagent

Question 10

What are the observations when acidified potassium dichromate reacts with aldehydes and ketones?

Answer 10

Ketones = no change.

Aldehyde = orange to green

Question 11

What are observations when Fehling’s solution is reacted with ketones and aldehydes?

Answer 11

Ketones = no change
Aldehyde = dark red precipitate

Question 12

What are observations when Tollen’s reagent is reacted with ketones and aldehydes?

Answer 12

Ketones = no change

Aldehyde = Silver Mirror produced.

Question 13

What are the reagents that can be used to test Carboxylic Acid? What are the corresponding observations?

Answer 13

Universal Indicator = pH of weak acid.

Reactive Metal = hydrogen effervescence (MASH)

Metal Carbonate = CO2 effervescence (CAWCS)