C8.1

Question 1

What is meant by the rate of a chemical reaction

Question 2

What are two ways to measure rates of reaction?

Answer 2

g/s and mol/s

Question 3

What is another unit that can be used to measure rates of reaction?

Answer 3

s/cm

Question 4

What does the graph label indicate when the reaction is fastest?

Answer 4

The graph label indicates the point where the reaction rate is at its maximum.

This is typically shown at the steepest part of the graph.

Question 5

What does the graph label indicate when the reaction is finished?

Answer 5

The graph label indicates the point where the reaction has completed and no further change occurs.

This is shown when the graph levels off.

Question 6

What does the rate of a chemical reaction indicate?

Answer 6

The rate of a chemical reaction tells you how fast reactants are turned into products.

Question 7

How can you calculate the rate of a reaction?

Answer 7

You can calculate the rate of a reaction by finding out how quickly the reactants are used up or how quickly the products are made.

Question 8

What can be plotted to show changes in reactants and products over time?

Answer 8

A graph can be plotted to show how the quantity of product formed or the quantity of reactant used up changes with time.

Question 9

What does the gradient of a tangent to the curve of the graph represent?

Answer 9

The gradient of a tangent to the curve of this graph at a specific time indicates the rate of the reaction at that time.

Question 10

What is produced when zinc reacts with hydrochloric acid?

Answer 10

Zinc chloride and hydrogen gas.

Question 11

Write the chemical equation for the reaction of zinc with hydrochloric acid.

Answer 11

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

Question 12

What does the graph show regarding the reaction?

Answer 12

The graph shows how the volume of hydrogen produced changes with time.

Question 13

What is the unit of measurement for the volume of gas produced in the graph?

Answer 13

Cubic centimeters (cm³).

Question 14

What is the unit of measurement for time in the graph?

Answer 14

Minutes.

Question 15

Explain how to calculate rate of reaction from a graph

Answer 15

Step 1
Draw a tangent to the curve
Make it long

Step 2
Construct a right angled triangle using the tangent as its longest side
Choose 2 points you can easily read the values of for corners of the triangle

Step 3
Calculate gradient of the tangent
Y-value/x-value

Question 16

What is the chemical reaction equation for calcium carbonate reacting with hydrochloric acid?

Answer 16

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

This reaction produces carbon dioxide, water, and calcium chloride.

Question 17

What happens to the mass of the reaction mixture as carbon dioxide is produced?

Answer 17

The mass of the reaction mixture decreases

This is due to the release of carbon dioxide gas.

Question 18

What is the initial rate of the reaction characterized by?

Answer 18

The rate of the reaction is fastest

This is indicated by the steepness of the tangent to the curve on a graph of mass against time.

Question 19

How does the gradient of the graph change as the reaction progresses?

Answer 19

The gradient decreases

This indicates that the reaction rate becomes slower over time.

Question 20

What does a gradient of zero indicate in the context of the reaction?

Answer 20

The reaction is finished

At this point, carbon dioxide is no longer being produced.

Question 21

Fill in the blank: At the start of the reaction, the gradient of the tangent to the curve is very _______.

Answer 21

steep

A steep gradient indicates a fast reaction rate.

Question 22

True or False: The reaction rate remains constant throughout the entire reaction.

Answer 22

False

The reaction rate slows down as the reaction progresses.

Question 23

How can you find out the rate of a chemical reaction?

Answer 23

By monitoring the amount of reactants used up over time or measuring the amount of products made over time

This involves measuring changes in concentration, volume, or pressure during the reaction.

Question 24

What two methods can be used to determine the rate of reaction?

Answer 24

• Monitoring the amount of reactants used up
• Measuring the amount of products made

Both methods require time as a factor for accurate measurement.