C7: Sustainable Chemistry

Question 1

What is meant by Bulk Chemical

Answer 1

a chemical produced on a large scale

Question 2

Give examples of Bulk Chemicals

Answer 2

Ammonia, sulfuric acid, sodium hydroxide and phosphoric acid

Question 3

What is meant by Fine Chemical

Answer 3

A chemical produced on a smaller scale

Question 4

Give examples of Fine Chemicals

Answer 4

Drugs, food additives and fragances

Question 5

Describe the five stages involved in producing chemicals in industry

Answer 5

Prepare feedstocks, synthesis, seperation of products, monitoring purity and handling by-products and wastes

Question 6

Give the 8 questions you should consider when deciding whether a process is sustainable

Answer 6

Will the raw materials run out?
How good is the atom economy?
What happens to the waste?
What are energy costs?
Will it damage environment?
What are health and safety risks?
Benefits/ risks to society?
Profitable?

Question 7

What is the difference between endothermic and exothermic reactions

Answer 7

In a exothermic reaction more energy is released breaking the bonds than required to break them. Where as in a endothermic reaction, the energy used to break bonds in greater than the energy released forming them.

Question 8

Explain in terms of energy how a catalyst works

Answer 8

Catalysts lower the activation energy of a reaction by providing another route

Question 9

What is a reversible reaction?

Answer 9

A reversible reaction is a reaction which goes both ways, the products of the reaction can themselves react to form the original reactants

Question 10

What is dynamic equilibruim

Answer 10

Where the reaction is taking place in both directions at exactly the same rate so that the overall effect is nill. This only works in a closed system

Question 11

Give two compromises made during the Haber process

Answer 11

High pressure favors the forward reaction, so the pressure is high enough for a good % yield but without being too expensive to maintain and build the plant.
Yield of ammonia is better in low temperatures, but the reaction would be slow. They compromise yield with speed of reaction.

Question 12

Explain why nitrogen fixation is important to food production and industry.

Answer 12

It turns nitrogen from the air into useful compounds such as ammonia. Ammonia is used to make fertilizers which increases crop yield helping to feed more people. It is also important for industry as helps in the production of plastics, explosives and pharmaceuticals

Question 13

What is the general formula for an Alkane

Answer 13

C n H 2n+2

Question 14

How does the reaction of ethanol and sodium differ to sodium and water

Answer 14

They are similar- sodium reacts more gently with ethanol than water which can even cause melting because of the heating of the metal

Question 15

Why is there a limit to the concentration of ethanol when made by fermentation

Answer 15

Ethanol is toxic to yeast, as the concentration reaches 10-20% the yeast die stopping the reaction

Question 16

How can concentration of ethanol be increased?

Answer 16

By distillation. The solution is heated in a fractionating column until the ethanol boils. The pure ethanol vapour reaches the top of the column where it then flows through a condenser cooling back to a liquid.

Question 17

How is ethanol made from crude oil?

Answer 17

Ethane a hydrocarbon found in crude oil is cracked to form ethene and hydrogen gas. Ethene will react with steam to make ethanol. The temperature needs 300 degrees and pressure of 70 atmospheres. Phosphoric acid is used as a catalyst

Question 18

What is the functional group for carboxylic acids

Answer 18

-COOH

Question 19

What do salts formed in reactions end in

Answer 19

-anoate EG. Ethanoate, methanoate

Question 20

What is the difference between plant oils and animal fats in terms of bonds within the molecules

Answer 20

Animal fats have mainly saturated hydrocarbon chains. They are normally solid at room temperature. Plant oils have mainly unsaturated hydrocarbon chains, they are liquid at room temperature.

Question 21

Describe in detail how you could get a pure ester

Answer 21

React a alcohol and carboxylic acid using a catalyst eg. sulfuric acid. You should heat the mixture under reflux. Then distill in a fractionating column. The impure ester can then be purified by pouring it in a tap funnel. React with sodium carbonate to remove acidic impurities. The lower layer can be tapped off. React with calcium chloride to remove any ethanol. It can be dried using anhydrous calcium chloride to absorb any water. Then filter out any solid calcium chloride.

Question 22

What is the difference between quantitative and qualitative?

Answer 22

qualitative tells you what it contains and quantitative how much it contains

Question 23

What is meant by ‘standard procedures’

Answer 23

they are agreed methods of working - they are chosen because they are the safest, most effective and accurate ways to use.

Question 24

What is meant by Retention time

Answer 24

The time it takes for a chemical to travel through the tube.

Question 25

What does the peak of a gas chromotography show

Answer 25

Shows how much of the chemical was in that sample