C2 - Acids & Bases, Making Ammonia Flashcards
(43 cards)
What is ammonia?
An alkaline gas made from nitrogen and hydrogen
What can ammonia be used to make?
Fertilizers and Nitric acid
What type of reaction is that that makes ammonia?
A reversible reaction
What process is used to make ammonia on a large scale?
The Haber process
What are the reactants in the Haber process?
Nitrogen and hydrogen
Show the symbol equation for the Haber process
N₂(g) + 3H₂⇌ 2NH₃
Show the word equation for the Haber process
nitrogen + hydrogen ⇌ ammonia
Why aren’t optimum conditions for the Haber process used?
Because they’d be very expensive to maintain
In the Haber process, what is the high pressure that the nitrogen and hydrogen is under?
200 atmospheres
In the Haber process, what is the temperature of the iron catalyst that the gases are passed over?
450°C
Around what percentage of the reactant gases in the Haber process make ammonia?
15%
What happens to the unreacted gases in the Haber process?
They are recylced.
What five things do the costs of making a new substance rely on?
The price of energy (gas and electricity), labour costs (wages for employees), how quickly the new substances can be made (cost of catalyst), the cost of starting materials (reactants), and the cost of equipment needed (plant and machinery)
What are the five factors that affect the cost of making a new substance, and why?
The pressure- the higher the pressure, the higher the plant cost, the temperature- the higher the temperature, the higher the energy cost, the catalysts- catalysts can be expensive to buy, but production costs are reduced because they increase the rate of reaction, the number of people needed to operate machinery- automation reduces the wages bill, the amount of unreacted material that can be recycled- recycling reduces costs.
What helps to determine the conditions used in the manufacture of chemicals?
Economic considerations
In the manufacture of chemicals, what must the percentage yield achieved be?
High enough to produce enough daily yield of product
In the manufacture of chemicals, what must the rate of reaction be?
High enough to produce enough daily yield of product
In the manufacture of chemicals, why should the optimum conditions be used?
To give the most economical reaction
In the Haber process, why isn’t a lower temperature (which increases yield) used?
Because the reaction is too slow
In the Haber process, why isnt a higher pressure (which increases yield) used
Because it becomes more expensive as yield increases
What role does the iron catalyst play in the Haber process?
It increases the rate of reaction, but doesn’t change the percentage yield
What are indicators?
Chemicals that change colour to show changes in pH
Give an example of an indicator that has only two colours
Litmus paper
Give an example of an indicator that has a range of colours over different pH values
Universal indicator
