C8.1-8.5

Question 1

What is the definition of rate of reaction?

Answer 1

Rate of reaction is the speed at which reactants are converted into products in a chemical reaction.

Question 2

How can you monitor the rate of reaction?

Answer 2

By safely describing and following a method to observe changes in concentration, volume, or mass over time.

Question 3

What are the units for rate of reaction?

Answer 3

Common units include moles per liter per second (mol/L/s) or grams per liter per second (g/L/s).

Question 4

How can the surface area of a solid be increased?

Answer 4

By breaking the solid into smaller pieces or grinding it into a powder.

Question 5

What is required for a chemical reaction to occur?

Answer 5

A collision with enough energy is necessary for a chemical reaction to take place.

Question 6

What factors can affect the rate of a chemical reaction?

Answer 6

Factors include temperature, concentration, surface area, and the presence of catalysts.

Question 7

How does temperature affect the rate of reaction?

Answer 7

Increasing temperature generally increases the rate of reaction by providing more energy for collisions.

Question 8

How can you safely conduct an experiment on temperature’s effect on rate of reaction?

Answer 8

By following a structured method that ensures safety and accurate measurement of reaction rates.

Question 9

Why are there different units for measuring rate of reaction?

Answer 9

Different units may be used depending on the context of the reaction and the substances involved.

Question 10

How do you calculate the mean rate of reaction?

Answer 10

By dividing the total change in concentration by the total time taken.

Question 11

How can you calculate the rate of reaction at a specific time?

Answer 11

By measuring the concentration of reactants or products at that specific time.

Question 12

How does changing the surface area affect the rate of reaction?

Answer 12

Increasing surface area allows more collisions to occur, thus increasing the rate of reaction.

Question 13

What is activation energy?

Answer 13

Activation energy is the minimum energy required for a reaction to occur.

Question 14

How do you calculate the surface area to volume ratio?

Answer 14

By dividing the surface area of an object by its volume.

Question 15

How does collision theory explain the effect of temperature on reaction rate?

Answer 15

Higher temperatures increase the energy and frequency of collisions, leading to a higher reaction rate.

Question 16

How can you plot a graph to calculate the gradient for initial rate of reaction?

Answer 16

By plotting concentration versus time and calculating the slope of the tangent at the start of the reaction.

Question 17

How can you justify a chosen method for monitoring the rate of reaction?

Answer 17

By explaining how the method effectively measures the changes in concentration or other relevant factors.

Question 18

Why do many collisions not lead to a chemical reaction?

Answer 18

Many collisions do not have sufficient energy or the correct orientation to result in a reaction.

Question 19

How can you calculate (1/t) and plot a graph with a meaningful line of best fit?

Answer 19

By measuring reaction times and plotting the inverse of time against concentration to analyze the relationship.

Question 20

can explain why there is more than
one unit for rate of reaction.

Answer 20

If you’re measuring how fast a concentration changes, the unit is mol/L/s.
If you’re measuring how fast a mass changes, the unit is g/s.
If you’re measuring how fast a volume changes (like gas), the unit is cm³/s.

Question 21

can use collision theory to explain in
detail how increasing surface area
increases the rate of reaction

Answer 21

Increasing surface area makes a reaction faster because it exposes more particles to collide with each other. More collisions mean the reaction happens more quickly. For example, when a solid is broken into smaller pieces, more of its surface is available for reactions, leading to a faster rate.

Question 22

How does changing concentration affect the rate of reaction?

Answer 22

Changing concentration can increase or decrease the rate of reaction depending on the reactants involved.

This is explained by collision theory.

Question 23

How does changing pressure affect the rate of gas phase reactions?

Answer 23

Changing pressure can affect the rate of gas phase reactions, typically increasing the rate by bringing reactant molecules closer together.

This is also explained by collision theory.

Question 24

What is a catalyst?

Answer 24

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.

Question 25

How does adding a catalyst affect the rate of reaction?

Answer 25

Adding a catalyst increases the rate of reaction by providing an alternative pathway with a lower activation energy. ## Footnote This is explained using collision theory.

Question 26

How can you safely investigate which catalyst is best for a reaction?

Answer 26

You can carry out a method that involves comparing the rates of reaction with different catalysts under controlled conditions.

Question 27

What is collision theory?

Answer 27

Collision theory explains how the rate of reaction is affected by the frequency and energy of collisions between reactant molecules.

Question 28

How do you calculate mean rates of reaction?

Answer 28

Mean rates of reaction can be calculated by dividing the change in concentration of a reactant or product by the time taken.

Question 29

How can you change gas pressure?

Answer 29

Gas pressure can be changed by altering the volume of the container or by changing the temperature.

Question 30

What is the industrial use of a catalyst?

Answer 30

Catalysts are used in industrial processes to increase reaction rates and improve efficiency, such as in the Haber process for ammonia production. ## Footnote Example: The use of iron as a catalyst in the Haber process.

Question 31

How do you interpret a rate of reaction graph?

Answer 31

You can interpret a rate of reaction graph by analyzing the slope at different points to determine the rate of reaction at specific times.

Question 32

Why does changing pressure have no effect on the rate of reaction for some reactions?

Answer 32

Changing pressure has no effect on the rate of reaction for some reactions because they do not involve gaseous reactants or products.

Question 33

How can you justify quantitative predictions in the effect of concentration on rate of reaction?

Answer 33

You can justify quantitative predictions by evaluating experimental data and discussing the relationship between concentration and reaction rate.

Question 34

What is a reaction profile diagram?

Answer 34

A reaction profile diagram illustrates the energy changes during a reaction, showing the effect of adding a catalyst on the activation energy.

Question 35

Why are catalysts justified in industry and household products?

Answer 35

Catalysts are justified in industry and household products because they enhance reaction rates, reduce energy consumption, and minimize waste.

Question 36

What is an enzyme?

Answer 36

An enzyme is a biological catalyst that speeds up biochemical reactions in living organisms by lowering the activation energy.

Question 37

can use collision theory to explain how adding a catalyst alters the rate of reaction.

Answer 37

Adding a catalyst increases the rate of reaction by providing an alternative pathway with a lower activation energy. This means that more particles can collide with enough energy to react, speeding up the reaction. The catalyst isn’t used up in the reaction, so it can keep helping the reaction happen faster.