Equilibria (triple) quiz

1. 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?

0.857 %

0.56 %

85.7 %

56 %

Question 1 of 15

2. In a sealed container, a reversible reaction can reach a state of ______________________________

Variable equilibrium

Static equilibrium

Constant equilibrium

Dynamic equilibrium

Question 2 of 15

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

Condensation

Diffusion

Combustion

Decomposition

Question 3 of 15

4. Explain why experimental values of enthalpy change differ from theoretical values

Different equipment produces different results. Heat energy is lost to the surroundings

Heat energy is lost to the surroundings. Not all the reactants are used up.

Different equipment produces different results. Heat energy is lost to the surroundings. Not all the reactants are used up

Different equipment produces different results. Not all the reactants are used up

Question 4 of 15

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

Blue

Cream

Purple

White

Question 5 of 15

6. 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 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 speeds up a chemical reaction but is chemically unchanged at the end of the reaction

Question 6 of 15

7. What will happen to the rate of reaction when we decrease pressure? A (g) + B (g) ⇋ C (g) (+∆H)

increase

it depends on the conditions

remain constant

decrease

Question 7 of 15

8. What does this diagram represent?

Energy level diagram for an exothermic reaction

Energy level diagram for an endothermic reaction

Reaction profile for an exothermic reaction

Reaction profile for an endothermic reaction

Question 8 of 15

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

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

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 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

Question 9 of 15

10. What is meant by the term activation energy?

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

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

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

The energy released by the reaction

Question 10 of 15

11. 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 warm temperatures (above 100⁰C)

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

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

Question 11 of 15

12. 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 NH₃ + HCl ⇌ NH₄Cl

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

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

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

Question 12 of 15

13. 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) less frequent collisions 3) decrease 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) more frequent collisions 3) decrease rate of reaction

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

Question 13 of 15

14. What does this symbol represent?

Reversible reaction

Yield of reaction is the same both ways

Rate of forward reaction equals rate of backwards reaction

Dynamic equilibrium

Question 14 of 15

15. 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 catalyst reduces the activation energy, and is not used up

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

Question 15 of 15

Equilibria (triple) quiz

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