Equilibria (triple) quiz

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

The particles fuse together

The reaction only goes partway

The reaction still occurs but very slowly

No reaction

Question 1 of 15

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

In a cool environment (below 0⁰C)

In a warm environment (above 0⁰C)

At constant pressure

In a sealed container

Question 2 of 15

3. 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) more frequent collisions 3) decrease rate of reaction

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

Question 3 of 15

4. What does the symbol ⇌ mean?

A reaction that requires a catalyst

Variable oxidation state

Reversible reaction

Equal amounts of reactants and products

Question 4 of 15

5. 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 5 of 15

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

Increases because the forward reaction is exothermic

Decreases because the backward reaction is endothermic

Increases because the backward reaction is endothermic

Decreases because the backward reaction is exothermic

Question 6 of 15

7. Describe the chemical test for water

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 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

Question 7 of 15

8. What does the symbol ΔH mean

enthalpy (energy) change

exothermic

heat energy

specific heat capacity

Question 8 of 15

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

Reagent

Ore

Solute

Catalyst

Question 9 of 15

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

Yellow ring of ammonium chloride

Steam formed as the reaction is exothermic

White gas formed

White solid formed

Question 10 of 15

11. 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 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

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

Question 11 of 15

12. 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

Different equipment produces different results. 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

Question 12 of 15

13. What is meant by the term endothermic?

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 which will only be spontaneous at warm temperatures (above 100⁰C)

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

Question 13 of 15

14. 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 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 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.

Question 14 of 15

15. 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 = (actual amount of products/theoretical amount of products)

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

Question 15 of 15

Equilibria (triple) quiz

Equilibria (triple) quiz

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