Equilibria (triple) quiz

1. 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 1 of 15

2. What does this symbol represent?

Dynamic equilibrium

Reversible reaction

Rate of forward reaction equals rate of backwards reaction

Yield of reaction is the same both ways

Question 2 of 15

3. What is meant by the term activation energy?

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

The energy released by the reaction

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

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

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) 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

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

Question 4 of 15

5. What will happen to the equilibrium position when the temperature is increased? Give a reason for your prediction. CH₄(g) + H₂O(g) ⇋ CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1

Equilibrium will move to the right because the forward reaction is exothermic

Equilibrium will move to the left because the forward reaction is endothermic

Equilibrium will move to the right because the forward reaction is endothermic

Equilibrium will move to the left because the forward reaction is exothermic

Question 5 of 15

6. Describe the chemical test for water

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

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

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

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

Question 6 of 15

7. 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 7 of 15

8. 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 in which heat energy is taken in (surroundings get colder)

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

Question 8 of 15

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

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. Heat energy is lost to the surroundings

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

Question 9 of 15

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

Decomposition

Condensation

Diffusion

Combustion

Question 10 of 15

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

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

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

Question 11 of 15

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

At constant pressure

In a warm environment (above 0⁰C)

In a sealed container

In a cool environment (below 0⁰C)

Question 12 of 15

13. 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 hydrochloride NH₃ + HCl ⇌ NH₃ClH

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

Question 13 of 15

14. 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 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 speeds up a chemical reaction but is used up as the reaction proceeds

Question 14 of 15

15. 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 %

56 %

0.857 %

0.56 %

Question 15 of 15

Equilibria (triple) quiz

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