Ammonia + Fertilisers

Question 1

how is ammonia manufactured in bulk?

Answer 1

Haber process
- liquid ammonia

Haber process factory
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0 page 10

Question 2

Haber Process optimal conditions
- temp
- pressure
- catalyst

Answer 2

• FIXED TEMP 450deg celc
• FIXED PRESSURE 200 atm
• finely divided iron catalyst

Catalyst speeds up both forward, backward reactions

Question 3

Haber Process
Raw materials
Equation forming Ammonia

Answer 3

Hydrogen
Nitrogen

N2 + 3H2 ⇌ 2Nh3

they are all gaseous state

(until they get cooled -> liquid ammonia)

Question 4

H____, N____

Haber Process
how to source for raw materials

Answer 4

Hydrogen: cracking of petroleum fractions
Nitrogen: fractional distillation, liquid air, when reach bp, nitrogen extracted

Question 5

Define reversible chemical reaction

Answer 5

reaction
- products can change back 2 original reactant
- under suitable conditions

Question 6

How choose conditions + definition optimal conditions for Haber process

Answer 6

compromise btwn
- max yield
- speed of reaction
- budget (energy costs), safety
- availibility of raw material

Optimal: produce good yield ammonia, acceptably fast rate reaction

Question 7

Decreasing temperature below optimal for Haber Process causes

Answer 7

Optimum
450degc

Advantage
better yield, ammonia

Disadvantage
slow down rate reaction

Question 8

Increasing pressure above optimal for Haber Process causes

Answer 8

Optimum
200atm

Advantage
Better yield ammonia
increase rate reaction

Disadvantage
Very expensive build plant
high pressure dangerous

Question 9

Haber process graph

Answer 9

https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0

Page 9

Question 10

Displace ammonia in a chemistry lab

Answer 10

displacement o ammonia from its salts
- base/alkali + ammonium salt
- release ammonia gas

Question 11

Why farmer add slaked lime/lime

Answer 11

neutralise excess acid, soil

Question 12

fertilisers contain…

Answer 12

nitrogen
potassium
phosphorous

Question 13

what ammonia for?

Answer 13

manufacture
1. cleaning agent
2. fertilisers (ammonium salts)

Question 14

common fertiliser compounds

Answer 14

ammonium salt/nitrates
1. ammonium nitrate
2. ammonium phosphate

3. potassium sulfate

Question 15

fertilisers for wat

Answer 15

1. add nitrogen 2 soil, improve plant growth
2. (fertliser formula) soluble, roots can absorb

SPAN for solublity check
1. Sodium
2. Potassium
3. Ammonium
4. Nitrate

Question 16

Y farmer cannot add alkali + ammonium salt 2gether?

Answer 16

1. alkali react w/ ammonium salts
2. produce ammonia gas, lost from soil
3. reduce amt nitrogen in soil
4. not maximised usage

neutralise -> add fertiliser
- make sure soil conducive, plant 2 grow

Question 17

can nitrogen react?

Answer 17

yes, but inert
- need high temp (450degc) react

no labtest for nitrogen.
need break 3ple bond

Question 18

in reversible reaction, when temp increase…

Answer 18

increase temp, favour backward reaction

vice versa.

Question 19

parts of Haber process machine

Answer 19

• main reactor
• cooling chamber

Question 20

desc backward reaction in ammonia

aka as reverse reaction

Answer 20

backward: ammonia decompose -> nitrogen, hydrogen

1. (product) decomposes -> (reactants)
2. no 100% yield.

Whenever writing abt reversible reaction
reaction goes forward, backward same time

Question 21

how to increase rate of reaction besides
1. increase temp
2. increase pressure

Answer 21

increase conc. reactants

Question 22

how separate ammonia from mixture of

ammonia
nitrogen
hydrogen

Answer 22

condensation

Question 23

if ammonia qn talk abt temperature/pressure correlation -> ammonia yield

Answer 23

Add FIXED
i.e. fixed pressure, temperature of 400atm, 200 deg, yield 50%

Question 24

ammonia dissociation eqn

Answer 24

Nh3 (aq) ⇌ OH- + Nh4+

most nh3 (aq) coz weak acid, partial dissociation