UNIT 3 - Fertilisers

Question 1

what do plants do when they grow?

Answer 1

they extract nutrients from the soil via their roots

Question 2

what happens to plants over time?

Answer 2

the level of nutrients that they contain decreases and the nutrients need to be replaced in order to grow healthy crops.

Question 3

what elements are essential for healthy plant growth?

Answer 3

the elements nitrogen, potassium, and phosphorus (NPK)

Question 4

what are the fertiliser compounds for nitrogen?

Answer 4

nitrates & ammonium salts

Question 5

what are the fertiliser compounds for phosphorus?

Answer 5

phosphates

Question 6

what are the fertiliser compounds for potassium?

Answer 6

potassium salts

Question 7

what must the fertiliser compounds be and why?

Answer 7

they must be soluble in water so that they can be taken up by the plant roots into the plant

Question 8

what does Δ stand for in the Haber process?

Answer 8

change in enthalpy

Question 9

what is the Haber process?

Answer 9

the industrial production of ammonia from nitrogen and hydrogen using an iron catalyst

Question 10

what is the word equation for the Haber process?

Answer 10

N₂ + 3H₂ <—> 2NH₃ ΔH = -92kJ

Question 11

why can true equilibrium not be achieved in the Haber process?

Answer 11

because it is a true open system

Question 12

what type of process is the Haber process?

Answer 12

a continuous process

Question 13

what does the catalyst do in the Haber process?

Answer 13

it provides a fast reaction rate and reasonable yield at lower temperature

Question 14

what is the rate of reaction like at low temperatures in the Haber process?

Answer 14

at low temperatures the forward rate of reaction is too slow to be economical

Question 15

what is the rate of reaction like at high temperatures in the Haber process?

Answer 15

at higher temperatures the rate of reaction increases but favours the reverse reaction

Question 16

what does high pressure favour in the Haber process?

Answer 16

it favours ammonia production but the required equipment is costly to build and maintain

Question 17

what must be reached in the Haber process?

Answer 17

compromises must be reached between the competing factors

Question 18

what does maximum yield require in the Haber process?

Answer 18

high pressure and low temperature

Question 19

how is the Haber process made cost-effective?

Answer 19

by using 200 atmospheres, 400°C and an IRON CATALYST, giving it a 15% yield

Question 20

how is a 98% yield achieved in the Haber process?

Answer 20

the ammonia produced is condensed and the unreacted gasses are recycled

Question 21

what are the starting materials in the Ostwalt process?

Answer 21

ammonia, oxygen and water

Question 22

what is manufactured in the Ostwalt process?

Answer 22

nitric acid

Question 23

how is a 98% yield achieved in the Ostwalt process?

Answer 23

by using a PLATINUM CATALYST

Question 24

how many tons of nitric acid are produced annually and for what purpose in the Ostwalt?

Answer 24

sixty million tons are produced for the manufacturing of explosives and fertilisers

Question 25

what temperature is the platinum catalyst in the Ostwalt process?

Answer 25

800°C

Question 26

what are ammonia and nitric acids?

Answer 26

important compounds used to produce soluble nitrogen containing salts

Question 27

how are fertilisers made?

Answer 27

by neutralisation reactions