Rate of reaction

Question 1

How can we interpret graphs?

Answer 1

End point of a reaction
Quantity of product
Quantity of reactant used
Effect of changing conditions

Question 1

How can we follow the progress of chemical reactions?

Answer 1

Changes in mass, volume and other quantities

Question 2

How can ROR be increased?

Answer 2

Increasing temp
Increasing concentration of a reactant
Increasing surface area/decreasing particle size
Use of a catalyst

Question 3

What are catalysts?

Answer 3

Substances used to speed up chemical reactions but can be recovered chemically unchanged at the end of the reaction

Question 4

How can ROR be shown to decrease over time?

Answer 4

Calculating the average rate at different stages of the reaction

Question 5

What are the four signs of a chemical reaction?

Answer 5

Colour change
Effervescence
Precipitation
Energy change

Question 6

What is reaction rate?

Answer 6

It describes how quickly a reaction progresses

Question 7

What effect does large particles have on reaction rate?

Answer 7

Small surface area
Fewer collisions
Slower reaction

Question 8

What effect does small particles have on reaction rate?

Answer 8

Large surface area
More collisions
Faster reaction

Question 9

What effect does low temp have on reaction rate?

Answer 9

Less energy
Fewer collisions
Slower reaction

Question 10

What effect does high temp have on reaction rate?

Answer 10

More energy
More collisions
Faster reaction

Question 11

What effect does low concentration have on reaction rate?

Answer 11

Less particles
Fewer collisions
Slower reaction

Question 12

What effect does high concentration have on reaction rate?

Answer 12

More particles
More collisions
Faster reaction

Question 13

What does higher rate equal?

Answer 13

Faster reaction

Question 14

Why is it useful to know the rate of reaction?

Answer 14

Safety (eg. Medicines, preventing explosions)
Economy (how quickly can a product be made and sold)

Question 15

How can we measure how much gas is being produced?

Answer 15

Inverted measuring cylinder filled with water
Gas syringe
Balance (used to measure mass loss)

Question 16

When is it not appropriate to use an inverted measuring cylinder?

Answer 16

Gas is water soluble

Question 17

How is ROR defined?

Answer 17

A change in some measurable quantity (mass, concentration, volume etc) over a period of time

Question 18

What can average rate be used to describe?

Answer 18

How quickly a reaction happens in a specific interval of time

Question 19

How can we complete a good experiment?

Answer 19

Repeat measurements
Calculate an average for repeat measurements
Measure accurately
Compare your results with literature data

Question 20

When is measuring mass loss a suitable method of measuring reaction rate?

Answer 20

For reactions which produce a gas less dense that air

Question 21

What does the slope of the graph correspond with?

Answer 21

Reaction rate

Question 22

What does steeper slope mean?

Answer 22

Higher rate

Question 23

Why does steeper slope mean higher rate?

Answer 23

Indicates the quantity of product formed is increasing more rapidly

Question 24

What does the height of the graph correspond with?

Answer 24

Quantity (volume or mass) of gas produced. Taller = more produce

Question 25

What are excess reagents?

Answer 25

Reactants that are not used up when the reaction is finished

Question 26

What happens when we add more of an excess reagent?

Answer 26

Will it produce more product

Question 27

Can changing concentration affect height?

Answer 27

Yes but only if the reactant is not in excess

Question 28

What is crucial when predicting rate graph shapes?

Answer 28

Take into account which reactants in excess, as adding ore of it will not affect the shape of the graph