C2e-manufacturing Chemicals: Making Ammonia Flashcards Preview

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Flashcards in C2e-manufacturing Chemicals: Making Ammonia Deck (18)
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1

What is the word equation for the haber process?

Nitrogen + hydrogen --> ammonia

2

What are the conditions needed for the haber process?

200 Atmospheres
450c
Iron catalyst

3

What is the balanced symbol equation for the haber process?

N2 + 3H2 --> 2NH3

4

What happens to the unreacted nitrogen and hydrogen?

They are recycled

5

How does a high pressure effect the percentage yield?

Increase percentage yield
Favour forward reaction
High pressures dangerous and expensive

6

How does a high temperature effect the percentage yield?

Favour reverse reaction
Decrease percentage yield
Low temperatures slow reaction rates
High rate of reacion

7

Why is 450c used?

Optimum temperature
Fast reaction rate
Reasonable percentage yield

8

What does an iron catalyst do?

Increases rate of reaction
Keeps costs down
Doesn't change percentage yield

9

What does the cost of making a new substance depend on?

Price of energy
Cost of starting materials
Wages
Equipment
How quickly substance can be made(cost of catalyst)

10

What is automation?

Putting robots in to make things

11

How do high pressures affect production costs?

Higher plant costs

12

How does high temperatures affect the production costs?

High energy cost

13

How does a catalyst affect the costs?

Reduces cost by increasing rate of reaction

14

How does automation affect costs?

Reduces wages bill

15

How do economic considerations determine the conditions used in the manufacture of chemicals?

-Rate and percentage yield must be high enough to give sufficient daily yield of product
-Low percentage yield can be accepted if reaction can be repeated alot with recycled starting materials
-optimum conditions used that give lowest cost rather than fastest reaction/ highest percentage yield

16

What is a reversible reaction?

A reaction that proceeds in both directions

17

What are the uses of ammonia?

Manufacture of fertilisers
Manufacture of nitric acid

18

What happens in the haber process?

Ammonia is made from nitrogen from the air and hydrogen that comes from cracking of oil fractions or from natural gas