Dynamic Equilibria Flashcards

All 14 cards in this deck

What is the word equation for the Haber process?

nitrogen + hydrogen $\rightleftharpoons$ ammonia

What is the balanced symbol equation for the Haber process?

$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$

What effect does adding a catalyst have on the rate of attainment of equilibrium and on the equilibrium yield?

Rate of attainment of equilibrium is increased; no effect on the equilibrium yield.

True or false? Using a catalyst in the Haber process increases the yield of ammonia at equilibrium.

False. Equilibrium is reached faster, but the equilibrium yield is unchanged.

How do increases in temperature, pressure and concentration each affect the rate at which equilibrium is reached?

Each one increases the rate, so equilibrium is reached faster.

Why is a compromise temperature used in the Haber process?

A lower temperature gives a higher yield of ammonia, but a higher temperature gives a faster rate — the compromise gives an acceptable yield in an acceptable time.

Why are very high pressures not used in industrial processes such as the Haber process, even though a higher pressure would give a higher yield of ammonia?

High pressures need strong, expensive equipment and a lot of energy, so costs rise too much.

Why are the raw materials for the Haber process, nitrogen and hydrogen, cheap to obtain?

Nitrogen comes from the air and hydrogen from natural gas, so both are readily available.

Which three elements are found in the compounds present in NPK fertilisers, to promote plant growth?

Nitrogen, phosphorus and potassium.

Which salt is formed when ammonia reacts with nitric acid?

Ammonium nitrate, used as a fertiliser.

What is the balanced equation for the reaction of ammonia with nitric acid?

$NH_3 + HNO_3 \rightarrow NH_4NO_3$

What are the steps in the laboratory preparation of ammonium sulfate?

e.g. from ammonia solution and dilute sulfuric acid

1. Titrate to find the volume of acid that exactly neutralises the ammonia solution (using an indicator).
2. Repeat with the same volumes but no indicator.
3. Evaporate/crystallise the solution to get ammonium sulfate crystals.

How does industrial production of ammonium sulfate differ from the laboratory preparation?

Industrially it is made on a much larger scale and needs several stages to make the ammonia and sulfuric acid from raw materials first.

True or false? Industrial production of ammonium sulfate is just the laboratory method scaled up in one step.

False. Industry must first produce ammonia (Haber process) and sulfuric acid from raw materials, so several stages are needed.