Enzymes

Question 1

What do enzymes do to the stains?

Answer 1

By breaking them down into smaller molecules they are either water-soluble, or are of size and polarity compatible with surfactants meaning that they can be suspended in solution.

Question 2

Define enzyme

Answer 2

Types of proteins that are biological catalysts that speed up the rate of a reaction and are not used up in the reaction. Each enzyme is specific in its action.

Question 3

What do enzymes do?

Answer 3

They catalyse chemical reactions to make the reaction easier to take place, and are not used up in the reaction.
They are fast acting as they have a high turnover number number, which means they can convert many molecules of substrates per unit time.

Question 4

How do enzymes help with the reactions?

Answer 4

They reduce the stability of bonds in reactants to speed up the reaction rate as enzymes reduce the input of energy required by lowering the activation energy needed for a reaction to take place, giving an alternative pathway.

Allow the reaction to take place at lower temps found in cells of organisms.

Question 5

What is the activation energy?

Answer 5

The amount of energy that must be absorbed by reactants so that a reaction can occur (Ea)

Question 6

What are the four factors that effect enzyme reaction?

Answer 6

Temperature
pH levels
Concentration of substrate
Concentration of enzymes

Question 7

How does high temperatures cause denaturation?

Answer 7

As high temps break hydrogen bonds that hold enzymes together

Question 8

What are the two main roles of washing powder?

Answer 8

Enzymes can perform two main roles in a laundry detergent:
effect stain removal
provide colour and fabric care

Question 9

Why is there only a small amount of washing powder needed?

Answer 9

Only a small amount of enzymes are required as enzymes can be reused over and over again. However this doesn’t mean that the same detergent solution can be used again multiple times, although they remain active, the finite amounts of other key ingredients limit the amount of soil that can be suspended in solution by each detergent dose. (saturation)

detergents can also contain enzyme stabilisers, which protect the enzymes and help them function.

Question 10

What else do enzymes do? (3)

Answer 10

Some enzymes act to smooth cotton fabrics by cleaving fibres that protrude from the surface. A smoother cotton surface means that soils are less readily taken up by fibres, and are more easily liberated. Enzymes can also help remove fuzz and pills, and can assist colour protection of fabrics

Question 11

What are the three controlled variables that are optimal for the ammonium process?

Answer 11

(i) medium temperature (≈500Cº)
(ii) very high pressure (≈250 atmospheres, ≈25,500kPa)
iii) Catalyst - a porous iron catalyst prepared by reducing magnetite, Fe3O4

Question 12

How does the catalyst work for the ammonium process? (Fe catalyst from Fe3O4)

Answer 12

a porous iron catalyst prepared by reducing magnetite, Fe3O4, which reacts with H2 and forms H2O, so it removes the Oxygen from the Fe so it becomes porous and powdered which increases surface area

Question 13

How does the catalyst help break down N2 and H2 to NH3?

Answer 13

As there is an increased S.A and the Nitrogen and Hydrogen can attach more easily. It first helps break N2 and H2 to single molecules and the molecules stick onto the catalyst till it meets with 3 hydrogens if it is a Nitrogen molecule (meeting place)

Question 14

What is another catalyst that can be used?

Answer 14

Osmium is a much better catalyst for the reaction but is very expensive.

Question 15

What is the Haber Process?

Answer 15

The Haber Process combines nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia.
The reaction is reversible and the production of ammonia is exothermic.

Question 16

What is the chemical equation for the ammonium process?

Answer 16

N₂ (g) + 3H₂ (g) ⇄ 2NH3(g) △H= -92 kJ mol-1

Question 17

What is the cofactor that helps with the catalyst for the ammonium process?

Answer 17

Contains potassium hydroxide added as a helper (cofactor, coenzyme, etc…) It is so the N₂ bonds and the H₂ bonds can be more readily broken

magnetite (Fe3O4) fused with smaller amounts of promoters consisting of other metal oxides. (inorganic catalyst)

Question 18

What is a catalyst?

Answer 18

(A substance that increases the rate of a reaction, by providing an alternative pathway and which is recoverable at the end unchanged in chemical composition or mass.)

Question 19

How can a rapid reaction for the catalyst to occur for the ammonium process?

Answer 19

it is grounded finely such that it has a large surface area of about 50 m2 g-1, and the magnetite is reduced to iron.

The large surface area allows gaseous molecules to rapidly absorb and react.

Question 20

What happens after the gases leave the reactor?

Answer 20

When the gases leave the reactor they are hot and at a very high pressure. Ammonia is easily liquefied under pressure as long as it isn’t too hot, and so the temperature of the mixture is lowered enough for the ammonia to turn to a liquid.

The nitrogen and hydrogen remain as gases even under these high pressures, and can be recycled.

Question 21

Describe the process of the haber process (6)

Answer 21

Nitrogen from air and hydrogen from natural gas combine

Nitrogen and hydrogen are 1:3 by volume

at 400-450C, 200atm with an iron catalyst

Gases are cooled and ammonia turn to liquid

Liquify ammonia

Unreacted gases are recycled