Equilibria (triple) quiz

1. State the expression for calculating % yield.

% yield = (actual amount of products/theoretical amount of products)

% yield = (theroretical amount of products/actual amount of products)

% yield = (actual amount of products/theoretical amount of products) x 100

% yield = (theroretical amount of products/actual amount of products) x 100

Question 1 of 15

2. What does the symbol ⇌ mean?

Equal amounts of reactants and products

A reaction that requires a catalyst

Variable oxidation state

Reversible reaction

Question 2 of 15

3. 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 reduces the activation energy, and is not used up

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

Question 3 of 15

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

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

Question 4 of 15

5. 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 heat energy is mixed evenly throughout all the water

To allow the heat to spread evenly through the copper container

To ensure the container does not get too hot

To prevent the water from evaporating

Question 5 of 15

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

Combustion

Diffusion

Condensation

Decomposition

Question 6 of 15

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

Blue

Purple

Cream

White

Question 7 of 15

8. What will happen to the equilibrium position when we decrease pressure? Give a reason for your prediction. A (g) + B (g) ⇋ C (g) (+∆H)

Equilibrium will shift to the left, because there are more molecules on the left hand side

Equilibrium will shift to the right, because there are more molecules of gas on the right hand side

Equilibrium will shift to the left, because there are more molecules of gas on the right hand side

Equilibrium will shift to the right, because there are more molecules of gas on the left hand side

Question 8 of 15

9. What is meant by the term exothermic?

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 9 of 15

10. 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 equal to the activation energy

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

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

Question 10 of 15

11. What does this diagram represent?

Energy level diagram for an endothermic reaction

Energy level diagram for an exothermic reaction

Reaction profile for an exothermic reaction

Reaction profile for an endothermic reaction

Question 11 of 15

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

Variable equilibrium

Constant equilibrium

Dynamic equilibrium

Static equilibrium

Question 12 of 15

13. Write a chemical equation for the reaction between hydrogen chloride and ammonia

2NH₃ + 2HCl ⇌ 2NH₃Cl + H₂

2NH₄ + 2HCl ⇌ 2NH₄Cl + H₂

NH₃ + HCl ⇌ NH₄Cl + H₂O

NH₃ + HCl ⇌ NH₄Cl

Question 13 of 15

14. 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) decrease rate of reaction

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

Question 14 of 15

15. 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 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

Question 15 of 15

Equilibria (triple) quiz

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