Haber Process - Seneca Flashcards
How can farmers benefit from the haber process ?
By reacting nitrogen with hydrogen, the Haber process yields ammonia. Nitrogen-based fertilisers can be made from this ammonia. Farmers can then add the fertiliser back into the soil.
What steps are taken in the haber process ?
1) Collect and purify nitrogen and hydrogen gases
2) pass over iron catalyst at 250 atmospheres pressure and 450 degrees Celsius- results in the production of ammonia gas + reversible so some break down into reactant
3) Condensation - The ammonia gas cools down in a condenser. The ammonia is removed from the condenser once it has become a liquid.
4) recycle - We can recycle any unused hydrogen and nitrogen back into the process to create more ammonia. This means that waste of valuable reactants can be avoided!
What is the equation for the haber process ?
N2(g) + 3H2(g) 2 NH3(g)
What pressure is used in the haber process ? Why can too high a pressure be hazardous ?
There are fewer molecules of product than reactant. This means that an increase in pressure moves the position of equilibrium towards the products.
Increasing the pressure also increases the rate of reaction, but high pressures are expensive and can be hazardous.of 200 atmospheres represents a happy medium between rate of ammonia production versus safety and cost.
What temperature is used in the haber process ?
The forward reaction is exothermic. This means that an increase in temperature moves the position of equilibrium towards the reactants.
So, there is a trade-off between increasing the rate of reaction by increasing the temperature and reducing the yield (because of the high temperature).As we have already seen, the end compromise is that a temperature of 450°C is used.
How does concentration affect the haber process ?
Increasing the concentration of a reactant, shifts the position of equilibrium so that more products are produced until equilibrium is reached again.
Increasing the concentration of a reactant favours the forward reaction.
Decreasing the concentration of a reactant, shifts the position of the equilibrium in the opposite direction to form more reactants. This lets the system return to equilibrium.
Decreasing the concentration of a product favours the backward reaction.
Why use a catalyst in the haber process?
A catalyst has no effect on the position in equilibrium.
A catalyst increases rates of reaction in both directions, so equilibrium is established faster.
Also a catalyst is not used up.
Why might the conditions needed for the haber process change ?
Commercially used conditions can change to account for changes to the cost and availability of energy supplies and raw materials.
What are NPK fertilisers and why are they used ?
Plants need nitrogen (N), phosphorus (P), and potassium (K) to grow.
Harvesting crops may mean that there isn’t enough of these elements in the soil. Fertilisers can help to top up these nutrients
Advantages of NPK fertilisers and what they contain.
Increase agricultural productivity :
Fertilisers increase the number of essential nutrients, resulting in an increase in agricultural productivity.
Contain NPK salts :
NPK fertilisers contain salts of all three essential elements in carefully controlled percentages.
How are nitrogen containing fertilisers produced ? Why are they ideal fertilisers ?
By oxidising ammonia
Ammonium nitrate reaction
Reacting nitric acid and ammonia together produces ammonium nitrate:
Ammonia + nitric acid → ammonium nitrate.
NH3(aq)+ HNO3(aq)→ NH4NO3(aq)
Nitrogen from 2 sources
Because it contains two sources of nitrogen, ammonium nitrate is ideal for use in fertilisers. Rich in nitrogen.
Things to consider in a chemical reaction.
To make chemicals manufacturing (making) feasible, we must consider these things:
Danger of fire
Is the reaction exothermic (releases heat) and can cause danger?
Danger of explosion
Does the high pressure mean an explosion could happen?
Energy requirements
Does the temperature have to be too high?
Cost of raw materials
Are the raw materials easy to access?
Catalyst use
Can we use a catalyst to reduce cost?
For what reason do Industrial reactions take place (financial).
Industrial reactions are only possible if the cost of making the chemical needed is suitable.
How is the fertiliser ammonium sulfate made ?
The fertiliser ammonium sulfate is produced in laboratories as well as through industrial production processes.
To make ammonium sulfate, sulfuric acid (H2SO4) and ammonia (NH3) are reacted together.
How is ammonium sulphate produced in a lab ?
(Titration) add a few drops of methyl orange indicator to ammonia. The solution will turn yellow.Slowly add dilute sulfuric acid (from the burette) to the ammonia until it turns red. Swirl the flask as you add.The colour change means that the solution has neutralised (and you have ammonium sulfate).
Purifying the solution
The solution you have produced has an indicator in it. This means it is not pure.To obtain a pure solution, repeat the experiment without using an indicator. You must add exactly the same amount of acid as in the first experiment.To get ammonium sulfate crystals, you must evaporate the solution until only a small amount is left. Once the solution has crystallised, filter out the crystals.
