Lesson 3.1.6a
3.1.6a Chemical equilibria, Le Chatelier’s principle and Kc Quiz: AQA Chemistry, Unit 1
20 questions
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Lesson 3.1.6a, Chemical equilibria, Le Chatelier’s principle and Kc: 20 multiple choice questions for the AQA Chemistry (7405), Unit 1: Physical chemistry, written with Revision Ninja.
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The 20 questions
-
In contrast to kinetics, what aspect of a chemical reaction does equilibrium describe?
- Activation energy
- Reaction mechanism
- Rate of reaction
- Extent of reaction
-
What relationship exists between forward and reverse reaction rates at chemical equilibrium?
- Both are zero
- They are equal
- Reverse rate higher
- Forward rate higher
-
What happens to reactant and product concentrations once dynamic equilibrium is reached?
- They reach zero
- They remain constant
- They become equal
- They constantly fluctuate
-
What process is represented by opposing double arrows in a chemical equation?
- Reversible reaction
- Exothermic reaction
- Catalysed reaction
- Irreversible reaction
-
What key industrial quantity can be predicted by studying chemical equilibrium position?
- Reaction rate
- Activation energy
- Equilibrium yield
- Enthalpy change
-
What word describes an equilibrium where forward and reverse reactions continue to occur?
- Irreversible
- Heterogeneous
- Static
- Dynamic
-
In a reaction at equilibrium, the forward rate is 4.0 x 10^-3 mol dm^-3 s^-1. What is the reverse rate?
- 0 mol dm^-3 s^-1
- 8.0 x 10^-3 mol dm^-3 s^-1
- 4.0 x 10^-3 mol dm^-3 s^-1
- 2.0 x 10^-3 mol dm^-3 s^-1
-
Which process goes essentially to completion rather than establishing a dynamic equilibrium?
- Haber process
- Ethanoic acid ionisation
- Methane combustion
- Contact process
-
Which industrial process is an example of a reversible equilibrium system?
- Neutralisation of acid
- Synthesis of ammonia
- Precipitation of silver
- Combustion of propane
-
What state is reached when concentrations in a closed system stop changing over time?
- Thermal decomposition
- Complete reaction
- Zero reaction rate
- Dynamic equilibrium
-
What feature increases the rate of reaching equilibrium without altering the equilibrium position?
- Higher pressure
- Catalyst
- Higher temperature
- Higher concentration
-
How does adding a catalyst affect the final yield of a reaction at equilibrium?
- Decreases yield
- Halves yield
- Increases yield
- No change
-
What happens to macroscopic properties like colour and pressure at dynamic equilibrium?
- They become zero
- They constantly fluctuate
- They double continually
- They stay constant
-
Which type of acid only partially ionises in water, establishing a dynamic equilibrium?
- Concentrated acid
- Weak acid
- Mineral acid
- Strong acid
-
For the simple reaction A <=> B, both steps are first order and the forward rate is kf[A] and the reverse rate is kr[B]. What is the equilibrium ratio [B]/[A]?
- [B]/[A] = kf/kr
- [B]/[A] = kf - kr
- [B]/[A] = kr/kf
- [B]/[A] = kf x kr
-
For the reaction 2A <=> B, the forward rate is kf[A]^2 and the reverse rate is kr[B]. At equilibrium [A] = 0.5 and [B] = 0.2 mol dm^-3, with kf = 0.4. What is kr?
- 0.1
- 0.5
- 0.2
- 2.0
-
What type of system is required for a reversible reaction to reach dynamic equilibrium?
- Open system
- Exothermic system
- Closed system
- Isolated system
-
What shifts when the temperature of a reaction at dynamic equilibrium is changed?
- Activation energy
- Empirical formula
- Position of equilibrium
- Catalyst activity
-
From which starting direction can a reversible reaction reach its dynamic equilibrium position?
- Neither direction
- Reverse direction only
- Forward direction only
- Either direction
-
At dynamic equilibrium, what is the net change in species concentration over time?
- Zero
- Fluctuates
- Increases
- Decreases
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