Chemistry Paper 2 Exam Questions with
Answers 100% Accuracy
List the factors that can affect the rate of a chemical reaction - Correct Answer Temperature
Concentration Surface area Pressure (if gas) Catalyst Light
Explain why the idea of activation energy is an important part of the collision theory used to explain rates of reaction - Correct Answer Activation energy = minimum energy needed for reactant particles to react as only those colliding particles with activation energy will react, so any collisions with insufficient energy will not react, so
no effect on rate of reaction
Why does increasing the temperature increase the rate of reaction? - Correct Answer Frequency of collisions increases, more particles collide with energy greater
than the activation energy in any given time
Acidic cleaners are used to remove lime scale (calcium carbonate) when they are used undiluted. They do not work as well when they are diluted. Explain this using your knowledge of collision theory. - Correct Answer There are many more collisions between acid particles in undiluted cleaner and lime scale in a given time resulting in faster reaction.
Because number of acid particles in a given volume is far higher in undiluted cleaner, causing more frequent collisions with particles of lime scale
Catalyst - Correct Answer a substance that increases the rate of a chemical reaction without being chemically changed
Evaluate the use of catalysts in the chemical industry - Correct Answer It speeds up production process leading to it being more economical, conserving energy resources because activation energy is lowered, which reduces costs.
There is also an added benefit of reducing pollution from fossil fuels, and saving our limited resources of fossil fuels, so catalysts make industrial processes more sustainable
Describe and explain the effect of increasing surface area on rate of reaction - Correct Answer If solid reactants are in smaller pieces, they have a greater surface area. Increasing surface area of solid reactants increases frequency of collisions between particles, increasing rate of reaction.
An example: Block of magnesium reacts with acid slower than magnesium powder
Reversible reaction - Correct Answer A chemical reaction in which the products re-
form the original reactants
When is dynamic equilibrium reached? - Correct Answer In a closed system, when the forward and reverse reactions occur at the same rate and the concentrations of reactants and products remain constant.
Describe Le Hotelier’s Principle - Correct Answer If a system is at equilibrium and a
change is made to any of the conditions, then the system responds to counteract change and restore the equilibrium.
Describe the effect of changing the concentration of reactants and products on the position of the equilibrium - Correct Answer If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
Describe the effect of changing temperature on the position of the equilibrium - Correct Answer If the temperature of a system at equilibrium is increased:
The relative amount of products at equilibrium increases for an endothermic reaction
The relative amount of products at equilibrium decreases for an exothermic reaction.
Describe the effect of changing pressure on the position of the equilibrium - Correct Answer This applies to equilibrium that involve gases
An increase in pressure causes the equilibrium position to shift towards the side with
the smaller number of molecules as shown by the symbol equation for that reaction.
A decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction.
Pressure has no effect on the reactions where the numbers of gas molecules are equal on both sides of the equation.
Describe the effect of a catalyst on the position of the equilibrium - Correct Answer No effect
It speeds up both forward and backward reactions equally
Equilibrium is achieved faster A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid.
What is common mistake when setting up the apparatus? - Correct Answer Delivery tube is in sulfuric acid So sulfuric acid will travel up tube No hydrogen gas will be collected
The activation energy for the reaction between zinc and sulfuric acid is lowered if a solution containing metal ions is added.
What is the most likely formula of the metal ions added?
Al3+, Ca2+, Cu2+, Na+ - Correct Answer Cu2+
A student adds a solution of ethnic acid to zinc carbonate in an open flask on a balance. Explain what happens to the mass of the flask and its contents during the reaction - Correct Answer Mass of flask and contents decreases Because carbon dioxide is produced Which escapes from the flask?
The rate of reaction is different when manganese dioxide is used as a fine powder rather than coarse lumps. Explain why. You should answer in terms of collision theory - Correct Answer because surface area of fine manganese dioxide powder is greater so there are more collisions with hydrogen peroxide particles per unit of time
The student measured the change in mass of the reactants. Describe another method, other than measuring the change in mass of the reactions
that the student could have used to find the rate of the reaction between marble chips and hydrochloric acid - Correct Answer Collect the gas in a gas syringe Measure the volume of gas
The reaction between solutions of iron (III) ions (Fe3+) and thiocyanate ions (SCN-) is reversible.
The color of the equilibrium mixture is orange at room temperature. Give the name of the solvent used to dissolve the ions in this reaction. - Correct Answer Water
A few drops of a colorless solution containing a high concentration of thiocyanate ions (SCN-) are added to the orange equilibrium mixture (water). Explain the color change observed. - Correct Answer It becomes redder Because the position of equilibrium moves to the right So that the increase in the concentration of thiocyanate ions is reduced
A water bath is set up at a temperature above room temperature. When a test tube containing the orange equilibrium mixture (water) is placed in the water bath, the mixture becomes more yellow.
Answers 100% Accuracy
List the factors that can affect the rate of a chemical reaction - Correct Answer Temperature
Concentration Surface area Pressure (if gas) Catalyst Light
Explain why the idea of activation energy is an important part of the collision theory used to explain rates of reaction - Correct Answer Activation energy = minimum energy needed for reactant particles to react as only those colliding particles with activation energy will react, so any collisions with insufficient energy will not react, so
no effect on rate of reaction
Why does increasing the temperature increase the rate of reaction? - Correct Answer Frequency of collisions increases, more particles collide with energy greater
than the activation energy in any given time
Acidic cleaners are used to remove lime scale (calcium carbonate) when they are used undiluted. They do not work as well when they are diluted. Explain this using your knowledge of collision theory. - Correct Answer There are many more collisions between acid particles in undiluted cleaner and lime scale in a given time resulting in faster reaction.
Because number of acid particles in a given volume is far higher in undiluted cleaner, causing more frequent collisions with particles of lime scale
Catalyst - Correct Answer a substance that increases the rate of a chemical reaction without being chemically changed
Evaluate the use of catalysts in the chemical industry - Correct Answer It speeds up production process leading to it being more economical, conserving energy resources because activation energy is lowered, which reduces costs.
There is also an added benefit of reducing pollution from fossil fuels, and saving our limited resources of fossil fuels, so catalysts make industrial processes more sustainable
Describe and explain the effect of increasing surface area on rate of reaction - Correct Answer If solid reactants are in smaller pieces, they have a greater surface area. Increasing surface area of solid reactants increases frequency of collisions between particles, increasing rate of reaction.
An example: Block of magnesium reacts with acid slower than magnesium powder
Reversible reaction - Correct Answer A chemical reaction in which the products re-
form the original reactants
When is dynamic equilibrium reached? - Correct Answer In a closed system, when the forward and reverse reactions occur at the same rate and the concentrations of reactants and products remain constant.
Describe Le Hotelier’s Principle - Correct Answer If a system is at equilibrium and a
change is made to any of the conditions, then the system responds to counteract change and restore the equilibrium.
Describe the effect of changing the concentration of reactants and products on the position of the equilibrium - Correct Answer If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
Describe the effect of changing temperature on the position of the equilibrium - Correct Answer If the temperature of a system at equilibrium is increased:
The relative amount of products at equilibrium increases for an endothermic reaction
The relative amount of products at equilibrium decreases for an exothermic reaction.
Describe the effect of changing pressure on the position of the equilibrium - Correct Answer This applies to equilibrium that involve gases
An increase in pressure causes the equilibrium position to shift towards the side with
the smaller number of molecules as shown by the symbol equation for that reaction.
A decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction.
Pressure has no effect on the reactions where the numbers of gas molecules are equal on both sides of the equation.
Describe the effect of a catalyst on the position of the equilibrium - Correct Answer No effect
It speeds up both forward and backward reactions equally
Equilibrium is achieved faster A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid.
What is common mistake when setting up the apparatus? - Correct Answer Delivery tube is in sulfuric acid So sulfuric acid will travel up tube No hydrogen gas will be collected
The activation energy for the reaction between zinc and sulfuric acid is lowered if a solution containing metal ions is added.
What is the most likely formula of the metal ions added?
Al3+, Ca2+, Cu2+, Na+ - Correct Answer Cu2+
A student adds a solution of ethnic acid to zinc carbonate in an open flask on a balance. Explain what happens to the mass of the flask and its contents during the reaction - Correct Answer Mass of flask and contents decreases Because carbon dioxide is produced Which escapes from the flask?
The rate of reaction is different when manganese dioxide is used as a fine powder rather than coarse lumps. Explain why. You should answer in terms of collision theory - Correct Answer because surface area of fine manganese dioxide powder is greater so there are more collisions with hydrogen peroxide particles per unit of time
The student measured the change in mass of the reactants. Describe another method, other than measuring the change in mass of the reactions
that the student could have used to find the rate of the reaction between marble chips and hydrochloric acid - Correct Answer Collect the gas in a gas syringe Measure the volume of gas
The reaction between solutions of iron (III) ions (Fe3+) and thiocyanate ions (SCN-) is reversible.
The color of the equilibrium mixture is orange at room temperature. Give the name of the solvent used to dissolve the ions in this reaction. - Correct Answer Water
A few drops of a colorless solution containing a high concentration of thiocyanate ions (SCN-) are added to the orange equilibrium mixture (water). Explain the color change observed. - Correct Answer It becomes redder Because the position of equilibrium moves to the right So that the increase in the concentration of thiocyanate ions is reduced
A water bath is set up at a temperature above room temperature. When a test tube containing the orange equilibrium mixture (water) is placed in the water bath, the mixture becomes more yellow.
