Equilibria (triple) quiz

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

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

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

Question 1 of 15

2. 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 ⇌ hydrated 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 ⇌ hydrous copper sulfate (blue)

Question 2 of 15

3. What is a catalyst?

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

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 3 of 15

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

In a warm environment (above 0⁰C)

In a sealed container

In a cool environment (below 0⁰C)

At constant pressure

Question 4 of 15

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

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

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

Question 5 of 15

6. What will happen to the rate of reaction when a catalyst is added? A (g) + B (g) ⇋ C (g) (-∆H)

decrease

remain constant

increase

it depends on the conditions

Question 6 of 15

7. Describe the chemical test for water

Add it to anhydrous potassium permanganate which will turn from white to purple if water is present

Add it to anhydrous copper(II) sulfate which will change from white to blue if water is present

Find the boiling point. If it is 100 ⁰C water is present

Find the melting point. If it is 0 ⁰C then water is present

Question 7 of 15

8. 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 8 of 15

9. 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 9 of 15

10. 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 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

Question 10 of 15

11. State and explain how increasing temperature affects the diffusion of a gas

Gas diffuses slower because the particles have less energy

Gas diffuses quicker because particles have more energy.

Gas diffuses quicker because there is less in its way

Gas diffuses slower because the particles collide more often with the air

Question 11 of 15

12. What does the symbol ΔH mean

enthalpy (energy) change

specific heat capacity

heat energy

exothermic

Question 12 of 15

13. What does the symbol ⇌ mean?

A reaction that requires a catalyst

Reversible reaction

Variable oxidation state

Equal amounts of reactants and products

Question 13 of 15

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

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

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

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

Question 14 of 15

15. Explain the effects of increasing the temperature on the rate of a reaction in terms of particle collision theory

1) particles have more kinetic energy 2) more frequent collisions 3) and a lower proportion of the collisions which occur have greater or equal to the activitation energy 4) increase rate of reaction

1) particles have more kinetic energy 2) more frequent collisions 3) and a higher proportion of the collisions which occur have greater or equal to the activation energy 4) increase rate of reaction

1) particles have less kinetic energy 2) less frequent collisions 3) and a lower proportion of the collisions which occur have greater or equal to the activitation energy 4) increase rate of reaction

1) particles have less kinetic energy 2) less frequent collisions 3) and a lower proportion of the collisions which occur have greater or equal to the activitation energy 4) decrease rate of reaction

Question 15 of 15

Equilibria (triple) quiz

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