Equilibria (triple) quiz

1. One feature of dynamic equilibrium is that there is no overall change in concentrations. What is the other?

The yield of the backward reaction is greater than 50%

The yield of the forwards reaction is greater than 50%

The rate of the forward reaction is equal to the rate of the backward reaction

The rate of the forward reaction is greater than the rate of the backward reaction

Question 1 of 15

2. For a reversible reaction to reach dynamic equilibria, where must the reaction take place?

At constant pressure

In a warm environment (above 0⁰C)

In a cool environment (below 0⁰C)

In a sealed container

Question 2 of 15

3. Explain the effects of increasing the surface area of a solid on the rate of a reaction in terms of particle collision theory

1) more particles exposed 2) less frequent collisions 3) increase rate of reaction

1) more particles exposed 2) more frequent collisions 3) increase rate of reaction

1) more particles exposed 2) less frequent collisions 3) decrease rate of reaction

1) more particles exposed 2) more frequent collisions 3) decrease rate of reaction

Question 3 of 15

4. What will happen to the yield of C when the pressure is increased? Give a reason for your prediction. A (g) + B (g) ⇋ C (g) (+∆H)

Decreases because there are fewer molecules on the left hand side

Decreases because there are fewer molecules on the right hand side

Increases because there are fewer molecules on the right hand side

Increases because there are fewer molecules on the left hand side

Question 4 of 15

5. With how much energy must two particles collide for a reaction to occur?

The particles must collide with an energy greater than the activation energy

The particles must collide with an energy less than the activation energy

The particles must collide with an energy equal to the activation energy

The particles must collide with an energy greater than or equal to the activation energy

Question 5 of 15

6. In a calorimetry experiment to investigate the heat energy released by the combustion of ethanol, why should the water in the calorimeter be stirred?

To prevent the water from evaporating

To ensure the heat energy is mixed evenly throughout all the water

To ensure the container does not get too hot

To allow the heat to spread evenly through the copper container

Question 6 of 15

7. What colour is anhydrous copper (II) sulfate?

Purple

Blue

White

Cream

Question 7 of 15

8. What does the symbol ⇌ mean?

Equal amounts of reactants and products

Reversible reaction

A reaction that requires a catalyst

Variable oxidation state

Question 8 of 15

9. What is a catalyst?

A substance that speeds up a chemical reaction but is chemically unchanged at the end of the reaction

A substance that speeds up a chemical reaction but is used up as the reaction proceeds

A substance that helps dissolve insoluble reagents to speed up the rate of reaction

A substance that slows down a chemical reaction but is chemically unchanged at the end of the reaction

Question 9 of 15

10. What is meant by the term endothermic?

A reaction in which heat energy is taken in (surroundings get colder)

A reaction which will only be spontaneous at cold temperatures (below 0⁰C)

A reaction in which heat energy is given out (surroundings get hotter)

A reaction which will only be spontaneous at warm temperatures (above 100⁰C)

Question 10 of 15

11. What does the symbol ΔH mean

enthalpy (energy) change

heat energy

specific heat capacity

exothermic

Question 11 of 15

12. In the thermal decomposition of calcium carbonate, we might expect 50g of calcium carbonate to produce 28g of calcium oxide. If instead only 24g of calcium oxide is produced, what is the percentage yield?

85.7 %

0.56 %

56 %

0.857 %

Question 12 of 15

13. Why a catalyst does not affect the position of equilibrium in a reversible reaction?

A catalyst reduces the activation energy, and is not used up

If a reversible reaction is in dynamic equilibrium, a catalyst increases the rate of the forward reaction and the rate of the backward reaction by the same amount, so the position of equilibrium is unaffected

A reaction in dynamic equilibrium already has the lowest possible activation energy

A catalyst has no effect on a forward or backward reactions if it is in dynamic equilibrium

Question 13 of 15

14. Gas particles move at a speed of several hundred metres per second at room temperature. Explain why gases take several minutes to diffuse across a room

Gas particles travel very slowly

Gas particles collide with air particles and move in random directions

Gas particles collide with air particles and move in only one direction

Gas particles are lazy and do not want to reach the other side of the room

Question 14 of 15

15. Ammonia and hydrogen chloride react together in a reversible reaction to produce a white solid. What are the word and symbol equations?

ammonia + hydrogen chloride ⇌ ammonium chloride + hydrogen 2NH₃ + 2HCl ⇌ 2NH₃Cl + H₂

ammonia + hydrogen chloride ⇌ ammonium chloride + water NH₃ + HCl ⇌ NH₄Cl + H₂O

ammonia + hydrogen chloride ⇌ ammonium chloride NH₃ + HCl ⇌ NH₄Cl

ammonia + hydrogen chloride ⇌ ammonium hydrochloride NH₃ + HCl ⇌ NH₃ClH

Question 15 of 15

Equilibria (triple) quiz

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