Equilibria (triple) quiz

1. What does the symbol ΔH mean

enthalpy (energy) change

exothermic

heat energy

specific heat capacity

Question 1 of 15

2. State the expression for calculating % yield.

% 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)

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

Question 2 of 15

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

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

Heat energy is lost to the surroundings. Not all the reactants are used up.

Question 3 of 15

4. 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 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

Question 4 of 15

5. 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 5 of 15

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

White gas formed

Yellow ring of ammonium chloride

Steam formed as the reaction is exothermic

White solid formed

Question 6 of 15

7. 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?

There is no overall change in concentrations

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%

Question 7 of 15

8. 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 8 of 15

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

Static equilibrium

Dynamic equilibrium

Constant equilibrium

Variable equilibrium

Question 9 of 15

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

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

A catalyst reduces the activation energy, and is not used up

Question 10 of 15

11. What will happen to the rate of reaction when we decrease temperature? A (g) + B (g) ⇋ C (g) + D (g) (+∆H)

remain constant

increase

it depends on the conditions

decrease

Question 11 of 15

12. What is meant by the term endothermic?

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

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

Question 12 of 15

13. What is a catalyst?

A substance that speeds up a chemical reaction but is used up as the reaction proceeds

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

A substance that speeds up a chemical reaction but is chemically unchanged at the end of the reaction

Question 13 of 15

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

Blue

Cream

White

Purple

Question 14 of 15

15. What is meant by the term activation energy?

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

The energy released by the reaction

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

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

Question 15 of 15

Equilibria (triple) quiz

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