C2g Flashcards Preview

Chemistry > C2g > Flashcards

Flashcards in C2g Deck (14):

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

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


What are the conditions for the haber process?

-200 atmospheres
-iron catalyst


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


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


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


What do production costs depend on?

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


What does optimum conditions mean?

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


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


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

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


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


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


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


What is meant by compromised conditions?

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


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