1. CHEMISTRY DEPARTMENT WAID ACADEMY EQUILIBRIUM

2. Which description shows the effect of a catalyst on the reaction rate and position of equilibrium in a reversible reaction? 1.A 2.B 3.C 4.D rate of forward reaction - increased rate of reverse reaction - unchanged position of equilibrium - moves to right rate of forward reaction - increased rate of reverse reaction - increased position of equilibrium - unchanged rate of forward reaction - increased rate of reverse reaction - decreased position of equilibrium - moves to right rate of forward reaction - unchanged rate of reverse reaction - unchanged position of equilibrium - unchanged 25

3. Chemical reactions are in a state of dynamic equilibrium only when 1.A 2.B 3.C 4.D the rate of the forward reaction equals the rate of the backward reaction. the concentrations of reactants and products are equal. the activation energies of the forward and backward reactions are equal. the reaction involves no enthalpy change.25

4. Under the conditions used industrially, ethene and steam react as follows:- Which set of conditions would give the best yield of ethanol at equilibrium? 1.High temperature, low pressure. 2.High temperature, high pressure. 3.Low temperature, high pressure. 4.Low temperature, low pressure. 25

5. In the Haber Process, illustrated by the equation below, the reaction never reaches equilibrium because 1.the ammonia is constantly removed. 2.an iron catalyst is used. 3.high pressure is used. 4.the temperature is held at about 500 o C 20

6. The equation refers to the preparation of methanol from synthesis gas. The formation of methanol is favoured by 1.low pressure and low temperature. 2.high pressure and low temperature. 3.high pressure and high temperature. 4.low pressure and high temperature 25

7. Which of these sets of changes shown will give the greatest increase in the proportion of solid in the equilibrium below? 1.A 2.B 3.C 4.D temperature - decrease pressure - decrease temperature - decrease pressure - increase temperature - increase pressure - decrease temperature - increase pressure - increase 25

8. When a reversible chemical reaction is at equilibrium. 1.The concentrations of reactants and products remain equal. 2.The forward reaction is unable to continue. 3.The concentrations of the reactants and products remain constant. 4.The forward and reverse reactions proceed at different rates.25

9. A catalyst is added to a reaction at equilibrium. Which of the following does not apply? 1.The rate of the forward reaction increases. 2.The rate of the reverse reaction increases. 3.The position of the equilibrium remains unchanged. 4.The position of the equilibrium shifts to the right. 25

10. Identify the statement which can be applied to the role of a catalyst in a reversible reaction. 1.It decreases the enthalpy change for the reaction. 2.It decreases the time for equilibrium to be established. 3.It alters the position of the equilibrium. 4.It increases the rate of the forward reaction more than the back reaction. 20

11. The addition of which substance would move the equilibrium below to the right? 1.Hydrogen. 2.Hydrogen chloride. 3.Sodium chloride. 4.Sodium hydroxide.25