Equilibria (triple) quiz

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

In a cool environment (below 0⁰C)

At constant pressure

In a warm environment (above 0⁰C)

In a sealed container

Question 1 of 15

2. State the observation in the reaction between HCl(g) and NH₃(g)

Steam formed as the reaction is exothermic

Yellow ring of ammonium chloride

White gas formed

White solid formed

Question 2 of 15

3. 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 collide with air particles and move in random directions

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

Gas particles travel very slowly

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

Question 3 of 15

4. What happens if two particles collide with less than the activation energy

No reaction

The particles fuse together

The reaction still occurs but very slowly

The reaction only goes partway

Question 4 of 15

5. What will happen to the yield of CH₃OH when the pressure is decreased? Give a reason for your prediction. CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = –91 kJ mol⁻1

Increases because there are more molecules on the left hand side

Increases because there are fewer molecules on the right hand side

Decreases because there are fewer molecules on the left hand side

Decreases because there are more molecules on the left hand side

Question 5 of 15

6. 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) increase 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) less frequent collisions 3) decrease rate of reaction

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

Question 6 of 15

7. What type of substance speeds up a chemical reaction but is chemically unchanged at the end of the reaction?

Catalyst

Solute

Reagent

Ore

Question 7 of 15

8. One feature of dynamic equilibrium is that the rate of the forward reaction is equal to the rate of the backward reaction. What is the other feature?

The yield of the forwards reaction is greater than 50%

The concentration of the products is increasing

The yield of the backward reaction is greater than 50%

There is no overall change in concentrations

Question 8 of 15

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

Purple

Blue

Cream

White

Question 9 of 15

10. What is meant by the term endothermic?

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

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

Question 10 of 15

11. 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 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 11 of 15

12. What does the symbol ΔH mean

specific heat capacity

enthalpy (energy) change

exothermic

heat energy

Question 12 of 15

13. 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 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

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

Question 13 of 15

14. State the expression for calculating % yield.

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

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

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

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

Question 14 of 15

15. What does the symbol ⇌ mean?

Variable oxidation state

Reversible reaction

A reaction that requires a catalyst

Equal amounts of reactants and products

Question 15 of 15

Equilibria (triple) quiz

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