An industrial plant synthesizes hydrogen fluoride, HF\text{HF}HF, gas by reacting hydrogen gas with fluorine gas.
Look at the equation for this reversible reaction:
H2(g)+F2(g)⇌2HF(g) \text{H}_2(\text{g}) + \text{F}_2(\text{g}) \rightleftharpoons 2\text{HF}(\text{g}) H2(g)+F2(g)⇌2HF(g)What is the volume of hydrogen gas, in dm3\text{dm}^3dm3, needed to react completely with 912 dm3912\text{ dm}^3912 dm3 of fluorine at room temperature and pressure? Use the balanced symbol equation to help you.
Calculate the volume of hydrogen fluoride formed, in dm3\text{dm}^3dm3, when 912 dm3912\text{ dm}^3912 dm3 of fluorine completely reacts with hydrogen at room temperature and pressure. Use the balanced symbol equation to help you.
Calculate the mass, in kilograms, of 912 dm3912\text{ dm}^3912 dm3 of fluorine at room temperature and pressure.
One mole of any gas occupies 24 dm324\text{ dm}^324 dm3.
Give your answer to 1 decimal place.
(The relative molecular mass, MrM_rMr, of F2\text{F}_2F2 is 38.038.038.0).
The reaction to make hydrogen fluoride is an equilibrium reaction:
H2(g)+F2(g)⇌2HF(g) \text{H}_2(\text{g}) + \text{F}_2(\text{g}) \rightleftharpoons 2\text{HF}(\text{g}) H2(g)+F2(g)⇌2HF(g)The forward reaction is exothermic.
The yield of hydrogen fluoride and the rate at which the reaction reaches equilibrium are affected by different conditions.
Look at two possible reaction conditions, A and B, the plant could use for this reaction.
| Temperature (∘C^\circ\text{C}∘C) | Pressure (atmospheres) | Catalyst? | |
|---|---|---|---|
| A | 250 | 2 | Yes |
| B | 500 | 8 | No |
The company decides to use reaction conditions A, instead of B.
Explain why they make this choice. Use ideas about rate of reaction and position of equilibrium to help you.
25 exam-style questions on OCR GCSE Chemistry Equilibria. Each one has a worked solution and a mark scheme showing where the marks go.