Equilibria (triple) quiz

1. What does this diagram represent?

Reaction profile for an endothermic reaction

Reaction profile for an exothermic reaction

Energy level diagram for an exothermic reaction

Energy level diagram for an endothermic reaction

Question 1 of 15

2. 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 %

0.857 %

56 %

0.56 %

Question 2 of 15

3. Explain the effects of increasing the concentration of solutions on the rate of a reaction in terms of particle collision theory

1) more particles in same space 2) more frequent collisions 3) decrease rate of reaction

1) more particles in same space 2) less frequent collisions 3) increase rate of reaction

1) more particles in same space 2) more frequent collisions 3) increase rate of reaction

1) more particles in same space 2) less frequent collisions 3) decrease rate of reaction

Question 3 of 15

4. What is meant by the term endothermic?

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

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

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

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

Question 4 of 15

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

White

Blue

Cream

Purple

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 ensure the container does not get too hot

To allow the heat to spread evenly through the copper container

To prevent the water from evaporating

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

Question 6 of 15

7. What name is given to the movement of gases?

Diffusion

Decomposition

Condensation

Combustion

Question 7 of 15

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

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

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

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

Question 8 of 15

9. What does the symbol ⇌ mean?

Reversible reaction

Variable oxidation state

A reaction that requires a catalyst

Equal amounts of reactants and products

Question 9 of 15

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

At constant pressure

In a sealed container

In a cool environment (below 0⁰C)

In a warm environment (above 0⁰C)

Question 10 of 15

11. What is meant by the term activation energy?

The energy provided by the catalyst to allow a reaction to proceed

The minimum energy that the particles in collision must have if a reaction is going to occur

The maximum energy of the final product for it to be stable

The energy released by the reaction

Question 11 of 15

12. The addition of water to anhydrous copper sulfate can be used to test for the presence of water. The reaction is reversible. What is the word equation? Describe the colour change.

anhydrous copper sulfate (white) + water ⇌ hydrous copper sulfate (blue)

anhydrous copper sulfate (blue) + water ⇌ hydrated copper sulfate (white)

anhydrous copper sulfate (blue) + water ⇌ hydrous copper sulfate (white)

anhydrous copper sulfate (white) + water ⇌ hydrated copper sulfate (blue)

Question 12 of 15

13. What is a catalyst?

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

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

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

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

Question 13 of 15

14. What will happen to the rate of reaction when the temperature and pressure is increased? Give a reason for your prediction. CH₄(g) + H₂O(g) ⇋ CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1

It depends on the conditions

The rate will remain constant

The rate will increase

The rate will decrease

Question 14 of 15

15. State two features of a reaction that is in dynamic equilibrium

1) The equilibrium is on the right hand side producing a greater concentration of product than reactant. 2) The rate of the forward reaction is equal to the rate of the backward reaction

1) The rate of the forward reaction is greater than the rate of the backward reaction. 2) there is no overall change in concentrations

1) The rate of the forward reaction is equal to the rate of the backward reaction. 2) There is no overall change in concentrations.

1) The concentrations of products and reactants are equal. 2) the rate of the forward reaction is equal to the rate of the backward reaction

Question 15 of 15

Equilibria (triple) quiz

Equilibria (triple) quiz

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