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iGCSE Chemistry: Equilibria - test myself

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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 collide with air particles and move in random directions
State and explain how increasing temperature affects the diffusion of a gas
Gas diffuses quicker because particles have more energy.
What name is given to the movement of gases?
Diffusion
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 yield?
86%
State the expression for calculating % yield.
% yield = (actual amount of products/theoretical amount of products) x100
Describe the chemical test for water
Add water to anhydrous copper(II) sulfate which will change from white to blue if water is present
What colour is anhydrous copper (II) sulfate?
White
What colour is hydrated copper (II) sulfate?
Blue
What does the symbol ⇌ mean?
Reversible reaction
What is the symbol for a reversible reaction?
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 chloride NH₃ + HCl ⇌ NH₄Cl
State the observation in the reaction between HCl(g) and NH₃(g)
White solid formed
The addition of water to anhydrous copper sulfate can be used to test for the presence of water. The reaction is reversible. What is the word equation? Describe the colour change.
anhydrous copper sulfate (white) + water ⇌ hydrated copper sulfate (blue)
Write a chemical equation for the reaction between hydrogen chloride and ammonia
anhydrous copper sulfate (white) + water ⇌ hydrated copper sulfate (blue)
(Triple only) For a reversible reaction to reach dynamic equilibria, where must the reaction take place?
In a sealed container
(Triple only) In a sealed container, a reversible reaction can reach a state of ______________________________
Dynamic equilibrium
(Triple only) 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
(Triple only) One feature of dynamic equilibrium is that there is no overall change in concentrations. What is the other?
The rate of the forward reaction is equal to the rate of the backward reaction
(Triple only) State two features of a reaction that is in dynamic equilibrium
1) The rate of the forward reaction is equal to the rate of the backward reaction. 2) There is no overall change in concentrations.
(Triple only) 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
(Triple only) What will happen to the equilibrium position when the pressure is decreased? Give a reason for your prediction.
CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = -91 kJ mol⁻1 Equilibrium will move to left the because there are more molecules on the left hand side
(Triple only) What will happen to the equilibrium position when the pressure 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 left because there are fewer molecules on the left hand side
(Triple only) What will happen to the equilibrium position when the temperature is decreased? Give a reason for your prediction.
CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = -91 kJ mol⁻1 Equilibrium will move to right the because the reaction is exothermic
(Triple only) What will happen to the equilibrium position when the temperature is increased? Give a reason for your prediction.
CO(g) + H₂O(g) ⇋ CO₂(g) + H₂(g) ΔH = -42 kJ mol⁻1 Equilibrium will move to left the because the reaction is exothermic
(Triple only) 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 endothermic
(Triple only) What will happen to the equilibrium position when we add catalyst? Give a reason for your prediction.
2A (s) + B (g) ⇋ C (g) + D (g) (-∆H) Equilibrium will not shift in position, because catalyst does not affect the position of equilibrium
(Triple only) What will happen to the equilibrium position when we add catalyst? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (-∆H) Equilibrium will not shift in position, because catalyst does not affect the position of equilibrium
(Triple only) What will happen to the equilibrium position when we add catalyst? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) + D (g) (+∆H) Equilibrium will not shift in position, because catalyst does not affect the position of equilibrium
(Triple only) What will happen to the equilibrium position when we decrease pressure? Give a reason for your prediction.
2A (s) + B (g) ⇋ C (g) + D (g) (+∆H) Equilibrium will shift to the right, because more molecules of gas on the right hand side
(Triple only) What will happen to the equilibrium position when we decrease pressure? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Equilibrium will shift to the left, because more molecules on the left hand side
(Triple only) What will happen to the equilibrium position when we decrease temperature ? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (-∆H) Equilibrium will shift to the right, because forward reaction is exothermic
(Triple only) What will happen to the equilibrium position when we decrease temperature? Give a reason for your prediction.
2A (s) + B (g) ⇋ C (g) + D (g) (+∆H) Equilibrium will shift to the left, because forward reaction is endothermic
(Triple only) What will happen to the equilibrium position when we decrease temperature? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) + D (g) (+∆H) Equilibrium will shift to the left, because forward reaction is endothermic
(Triple only) What will happen to the equilibrium position when we increase pressure ? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (-∆H) Equilibrium will shift to the right, because there are fewer molecules on the right hand side
(Triple only) What will happen to the equilibrium position when we increase pressure ? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) + D (g) (+∆H) Equilibrium will not shift in position, because same number of molecules on each side
(Triple only) What will happen to the equilibrium position when we increase pressure? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) + D (g) (-∆H) Equilibrium will not shift in position, because same number of molecules on each side
(Triple only) What will happen to the equilibrium position when we increase temperature? Give a reason for your prediction.
2A (s) + B (g) ⇋ C (g) + D (g) (-∆H) Equilibrium will shift to the left, because forward reaction is exothermic
(Triple only) What will happen to the equilibrium position when we increase temperature? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Equilibrium will shift to the right, because forward reaction is endothermic
(Triple only) What will happen to the equilibrium position when we increase temperature? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (-∆H) Equilibrium will shift to the left, because forward reaction is exothermic
(Triple only) What will happen to the rate of reaction when the temperature and pressure is increased? Give a reason for your prediction.
CH₄(g) + H₂O(g) ⇋ CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1 The rate will increase
(Triple only) What will happen to the rate of reaction when we add catalyst?
A (g) + B (g) ⇋ C (g) (-∆H) increase
(Triple only) What will happen to the rate of reaction when we add catalyst?
A (g) + B (g) ⇋ C (g) + D (g) (+∆H) increase
(Triple only) What will happen to the rate of reaction when we decrease pressure?
A (g) + B (g) ⇋ C (g) (+∆H) decrease
(Triple only) What will happen to the rate of reaction when we decrease temperature?
A (g) + B (g) ⇋ C (g) + D (g) (+∆H) decrease
(Triple only) What will happen to the rate of reaction when we increase pressure ?
A (g) + B (g) ⇋ C (g) (-∆H) increase
(Triple only) What will happen to the rate of reaction when we increase temperature?
A (g) + B (g) ⇋ C (g) (+∆H) increase
(Triple only) What will happen to the yield of C when the pressure is decreased? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Decreases, because there are more molecules on the left hand side
(Triple only) What will happen to the yield of C when the pressure is increased? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Increases because there are fewer molecules on the right hand side
(Triple only) What will happen to the yield of C when the temperature is decreased? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Decreases because the backward reaction is exothermic
(Triple only) What will happen to the yield of C when the temperature is increased? Give a reason for your prediction.
A (g) + B (g) ⇋ C (g) (+∆H) Increases because the forward reaction is endothermic
(Triple only) What will happen to the yield of CH₃OH when the pressure is decreased? Give a reason for your prediction.
CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = -91 kJ mol⁻1 Decreases because there are more molecules on the left hand side
(Triple only) What will happen to the yield of CH₃OH when the pressure is increased? Give a reason for your prediction.
CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = -91 kJ mol⁻1 Increases because there are fewer molecules on the right hand side
(Triple only) What will happen to the yield of CH₃OH when the temperature is decreased? Give a reason for your prediction.
CO(g) + 2H₂(g) ⇋ CH₃OH(g) ΔH = -91 kJ mol⁻1 Increases because the forward reaction is exothermic
(Triple only) 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 Decreases because the backward reaction is endothermic