C2g Flashcards Preview

Chemistry > C2g > Flashcards

Flashcards in C2g Deck (14):
1

Where does the hydrogen and nitrogen for the haber process come from?

-nitrogen from air
-hydrogen from cracking oil fractions and natural gas

2

What are the conditions for the haber process?

-200 atmospheres
-450C
-iron catalyst

3

Why can't the pressure be too high or low in the haber process?

-high pressure increases the percentage yield of a reaction
-but requires expensive material to handle the pressure and is dangerous

4

Why can't the temperature be too high or too low in the haber process?

-high temperature, speeds up reaction and decreases the percentage yield
-low temperature slows reaction but increases yied

5

Why is a catalyst used in the haber process?

-to speed up the reaction
-which gets it to equilibrium proportions faster (catalyst doesn't affect the position of equilibrium)
-without catalyst temperature would need raising

6

What do production costs depend on?

-price of energy
-cost of raw materials
-labour costs
-plant costs (equipment)
-rate of reduction

7

What does optimum conditions mean?

-condition that give the lowest production cost per kg of product

8

How does the price of energy affect the cost of production?

-industries need to keep energy bills low
-if reaction needs high temperature, running cost will be higher

9

How does the cost of raw materials affect the cost of production?

-keep this at a minimum by recycling un-reacted materials

10

How does the labour costs affect the cost of production?

-everyone working in the company needs payment
-labour-intensive process(i.e require many people) can be expensive
-automation cuts running costs by reducing the number of people involved
-companies must always weigh savings on wage bills against initial cost and running cost of machinery

11

How does the plant (equipment) cost affect the cost of production?

-cost of equipment depends on conditions it has to cope with
-equipment that can deal with very high pressures are more expensive than equipment needed to deal with atmospheric pressure

12

How does the rate of production affect the cost of production?

-the faster the rate of reaction the the less time and costs spent on production
-rates of reactions often increased by catalysts
-increase in production rate has to balance the cost of buying a catalyst and replacing any that get lost

13

What is meant by compromised conditions?

-optimum temperature that gives fast reaction rate and reasonable percentage yield
-its a compromise

14

What is the process of the haber process?

1-hydrogen and nitrogen enter at ratio of 3:1
2-heated at 450C, put under pressure at 200atm and catalysed by trays of iron in a reaction vessel
3-condenser at the bottom to condense the now ammonia into liquid
4-liquid ammonia is removed to stop reaction from reversing
4-the unused reactants stay as gases and are recycled