Chapter 10 Rate of reaction

Question 1

What is meant by rate of reactionx2

Answer 1

how fast a reactant is used up
or how fast a product is formed

Question 2

Equation for rate of reaction

Answer 2

rate= change in concentration÷ time

Question 3

unit for ‘theoretical’ rate of reaction

Answer 3

moldm^-1s^-1

Question 4

Factors affecting RoR

Answer 4

Temp
Concentration (or pressure with liquids)
Presence of a catalyst
Surface area of solids

Question 5

Collision theory?

Answer 5

For a reaction to occur , particles must come together and collide with the correct orientation and an energy greater than the activation energy of the reaction

Question 6

Explain affect of higher concentration/increased pressure

Answer 6

More particles in a given volume so more FREQUENT collisions so faster RoR

Question 7

What is the criteria for the properties we can measure to find RoR 2

Answer 7

Changes during the reaction
Proportional to conc

Question 8

When monitoring RoR by has collection when should the stop clock be started

Answer 8

when bung is replaced

Question 9

Two methods of monitoring RoR when a gas is produced

Answer 9

Gas collection
Mass loss

Question 10

why is cotton wool used in the monitoring by mass loss experiment and why will it have no negative affect on the experiment

Answer 10

Stop spray of solution caused by fizzing escaping, permeable enough to let gas escape

Question 11

Catalyst?

Answer 11

substance that increases rate of chemical reaction without undergoing any permanent change itself

Question 12

Characteristics of catalysts 4

Answer 12

Not used up in the chemical reaction
May react with the reactant to form an intermediate
May provide a surface of which the reaction takes place
At the end of a reaction it is always regenerated

Question 13

How do catalysts increase RoR

Answer 13

Provides an alternative reaction pathway with a lower activation energy

Question 14

Symbol for activation energy with the presence of a catalyst

Answer 14

E sub c

Question 15

Homogeneous catalyst?

Answer 15

Has same physical state as the REACTANTS

Question 16

Example of when homogeneous catalyst is used

Answer 16

Ozone depletion

Question 17

Heterogeneous catalyst

Answer 17

Catalyst has a different physical state from the reactants

Question 18

Adsorption

Answer 18

Formation of weak bonds with the catalyst surface during use of a heterogeneous catalysts

Question 19

Steps in the use of a heterogeneous catalyst

Answer 19

Adsorption
Bonds within reactant molecules break
New bonds form to produce product molecules
Desorption

Question 20

Desorption

Answer 20

Product molecules leave the surface of a heterogeneous catalyst

Question 21

Economic and environmental importance of catalysts 4

Answer 21

Catalyst increase the rate of industrial chemical reactions
Lower temps required for reactions
Less electricity from combustion of fossil fuels required
Less combustion of fossil fuels so fewer emmissions of CO2 and other pollutants

Question 22

Limitations of some industrial catalysts, and why they are still used

Answer 22

Some are toxic
Benefits outweigh risks

Question 23

Examples of toxic catalysts 3

Answer 23

Rhodium, Palladium, platinum