Reversible Reactions & Equilibria Practice Questions

Name the raw material from which each of these gases is obtained.

nitrogen: ...........................

hydrogen: ...........................

State the temperature and the pressure used in the Haber process.

Which metal is used as the catalyst in the Haber process?

Put a cross ( ☒ ) in the box next to your answer.

☐ A aluminium

☐ B iron

☐ C nickel

☐ D platinum

What does the symbol $\rightleftharpoons$ in this equation show?

Put a cross ( ☒ ) in the box next to your answer.

☐ A the reaction gives out heat

☐ B the reaction is reversible

☐ C the reaction needs a catalyst

☐ D the reaction is complete

Explain why a white solid forms near the cooler, open end of the test tube.

Explain what is meant by dynamic equilibrium.

Explain why this equilibrium can only be reached if the flask is sealed.

Explain the effect of increasing the pressure on the yield of methanol at equilibrium.

State the effect, if any, of adding a catalyst on the yield of methanol at equilibrium.

State the colour change seen when dilute acid is added to the yellow solution.

Sodium hydroxide solution is added to the orange mixture. The sodium hydroxide reacts with and removes $\mathrm{H^+}$ ions.

Explain what you would see.

Describe how the student could then show that this reaction is reversible.

Explain how the student's observations show that this reaction is reversible.

A second student heats the same mass of pink crystals in a sealed tube. The solid does not turn completely blue.

Explain why.

Write the balanced equation, including state symbols, for the reversible reaction between nitrogen and hydrogen to form ammonia, $\mathrm{NH_3}$.

Use the data in the table to deduce whether the forward reaction is exothermic or endothermic. Explain your answer.

Use the data and your equation to explain why the yield of ammonia increases as the pressure is increased.

Sulfur trioxide is made from sulfur dioxide and oxygen in a reversible reaction.

$$\mathrm{2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)}$$

The forward reaction is exothermic.

A company makes sulfur trioxide at a temperature of $450\ ^\circ\mathrm{C}$ and a pressure of $2$ atmospheres. An engineer suggests changing the conditions to a temperature of $250\ ^\circ\mathrm{C}$ and a pressure of $10$ atmospheres.

Explain, in terms of the position of equilibrium, how each of these changes would affect the yield of sulfur trioxide at equilibrium.