Fertilisers

Question 1

Which elements do plants need for healthy growth

Answer 1

Nitrogen (N), Phosphorus (P), Potassium (K)

Question 2

Why are fertilisers added to soil

Answer 2

To supply essential nutrients and increase crop yield.

Question 3

What are natural fertilisers

Answer 3

Fertilisers from natural sources such as compost or manure.

Question 4

Why do natural fertilisers often have lower nutrient availability?

Answer 4

Nutrients are locked in complex structures

Question 5

What are synthetic fertilisers

Answer 5

Soluble salts produced chemically

Question 6

Why are synthetic fertilisers widely used

Answer 6

They contain higher nutrient levels and are cheaper

Question 7

What properties make a compound suitable as a fertiliser

Answer 7

High nutrient content
Highly soluble in water.

Question 8

How are many synthetic fertilisers made

Answer 8

By neutralisation reactions

Question 9

Which ions are commonly present in fertilisers

Answer 9

Ammonium (NH₄⁺)
Nitrate (NO₃⁻)

Question 10

What is the formula of ammonia

Answer 10

NH₃.

Question 11

What are the properties of ammonia

Answer 11

Colourless gas
Toxic
Sharp unpleasant smell
Highly soluble in water.

Question 12

What happens when ammonia dissolves in water

Answer 12

It forms an alkaline solution

Question 13

What colour does ammonia turn pH paper or universal indicator

Answer 13

Blue

Question 14

What type of substance is ammonia in reactions

Answer 14

A base

Question 15

What is unusual about ammonia neutralisation reactions

Answer 15

Only a salt is produced (no water)

Question 16

Give examples of fertiliser salts produced using ammonia

Answer 16

Ammonium nitrate (NH₄NO₃)
Ammonium sulfate ((NH₄)₂SO₄)
Ammonium phosphate ((NH₄)₃PO₄).

Question 17

What is the main use of ammonia

Answer 17

Manufacture of fertilisers

Question 18

Other uses ammonia

Answer 18

Manufacture of nitric acid
Cleaning products
Explosives

Question 19

What industrial process produces ammonia

Answer 19

The Haber process

Question 20

What are the reactants in the Haber process

Answer 20

Nitrogen and hydrogen

Question 21

What is the product of the Haber process

Answer 21

ammonia

Question 22

What is the Haber process reaction

Answer 22

N₂ + 3H₂ ⇌ 2NH₃

Question 23

What reacts in the Haber process

Answer 23

Nitrogen + hydrogen → ammonia

Question 24

What type of reaction is the Haber process

Answer 24

Reversible reaction

Question 25

What conditions are used in the Haber process

Answer 25

Temperature: ~450°C Pressure: ~200 atm Catalyst: iron

Question 26

Why are the Haber process conditions a compromise

Answer 26

To balance reaction rate and ammonia yield

Question 27

Why is low temperature not used in haber process

Answer 27

High yield but reaction is too slow.

Question 28

Why is high temperature not used in haber process

Answer 28

Fast reaction but low yield of ammonia

Question 29

Why is high pressure not fully used

Answer 29

It gives high yield but is expensive and dangerous.

Question 30

Why are Haber conditions a compromise?

Answer 30

High temperature → faster reaction but lowers yield High pressure → increases yield but is expensive → So a compromise is used.

Question 31

What catalyst is used in the Haber process

Answer 31

Iron

Question 32

What helps increase ammonia yield besides the catalyst

Answer 32

Recycling unreacted gases

Question 33

What industrial process produces nitric acid

Answer 33

The Ostwald process

Question 34

What reactants are used in the Ostwald process

Answer 34

Ammonia, oxygen and water

Question 35

What is produced in the Ostwald process

Answer 35

Nitric acid

Question 36

What catalyst is used in the Ostwald process

Answer 36

platinum

Question 37

Why is ammonia important in fertiliser production

Answer 37

is used to make nitric acid and ammonium fertilisers

Question 38

What does the Ostwald process do

Answer 38

Converts ammonia into nitric acid.

Question 39

Ammonia + acid

Answer 39

NH₃ + HCl → NH₄Cl

Question 40

Ammonia + nitric acid

Answer 40

NH₃ + HNO₃ → NH₄NO₃

Question 41

How can the Haber process be made more economical

Answer 41

Use a catalyst Recycle unreacted gases Use compromise conditions

Question 42

How does a catalyst make the Haber process more economical

Answer 42

Speeds up the reaction → saves time and energy

Question 43

How does recycling gases make haber more economical

Answer 43

Unreacted nitrogen and hydrogen are reused → less waste

Question 44

Why are compromise conditions more economical

Answer 44

They balance yield, rate, and cost → avoids wasting energy/money.

Question 45

How is the Ostwald process made more economical

Answer 45

Use a catalyst Use ammonia efficiently

Question 46

How does a catalyst help in the Ostwald process

Answer 46

Speeds up the reaction → reduces energy costs