Equilibria (triple) quiz

1. 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) x 100

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

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

Question 1 of 15

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

The reaction still occurs but very slowly

The reaction only goes partway

The particles fuse together

No reaction

Question 2 of 15

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

2NH₄ + 2HCl ⇌ 2NH₄Cl + H₂

NH₃ + HCl ⇌ NH₄Cl + H₂O

NH₃ + HCl ⇌ NH₄Cl

2NH₃ + 2HCl ⇌ 2NH₃Cl + H₂

Question 3 of 15

4. 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) 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) increase rate of reaction

1) more particles in same space 2) more frequent collisions 3) decrease rate of 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 allow the heat to spread evenly through the copper container

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

To prevent the water from evaporating

To ensure the container does not get too hot

Question 5 of 15

6. 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 6 of 15

7. 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 only one direction

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

Gas particles travel very slowly

Gas particles collide with air particles and move in random directions

Question 7 of 15

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

Constant equilibrium

Static equilibrium

Variable equilibrium

Dynamic equilibrium

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 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 helps dissolve insoluble reagents to speed up the rate of reaction

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

Question 10 of 15

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

Purple

White

Blue

Cream

Question 11 of 15

12. What will happen to the equilibrium position when we add a catalyst? Give a reason for your prediction. A (g) + B (g) ⇋ C (g) + D (g) (+∆H)

Equilibrium will not shift in position, because catalyst does not affect the position of equilibrium

Equilibrium will move to the right, because a catalyst increases the backward rate of reaction

Equilibrium will move to the left, because a catalyst increases the forward rate of reaction

Equilibrium will move to the right, because a catalyst increases the forward rate of reaction

Question 12 of 15

13. 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

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 reaction in dynamic equilibrium already has the lowest possible activation energy

Question 13 of 15

14. What is meant by the term exothermic?

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)

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

Question 14 of 15

15. What does the symbol ⇌ mean?

Equal amounts of reactants and products

Reversible reaction

A reaction that requires a catalyst

Variable oxidation state

Question 15 of 15

Equilibria (triple) quiz

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