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Flashcards in Section 1 Deck (39):
1

Why is controlling the rate of reaction in industrial processes important?

-if the reaction is too slow it takes too long so profit is lowered or the process is not economically viable
-if the process is too quick then there is a risk of thermal explosion

2

What are five factors affecting the rate of reaction?

-concentration
-pressure
-particle size
-temperature
-catalyst

3

How does increasing concentration affect the rate of reaction?

It increases the rate of reaction

4

How does increasing pressure affect the pressure of a gaseous reaction?

It increases the rate of reaction

5

How does decreasing the particle size affect the rate of reaction?

It increases rate of reaction (more surface area)

6

How does increasing temperature affect the rate of reaction?

It increases the rate of reaction

7

What does adding a catalyst do to the rate of reaction?

It increases the rate of reaction

8

What are the two features necessary of reactants for collision theory?

-reactants must collide with each other in the correct orientation
-the collision must have sufficient energy

9

Use collision theory to describe how concentration affects rate of reaction

A more concentrated acid has more particles so allows more collisions between acid and solid. More of these collisions will have sufficient energy and correct orientation for a reaction to occur and since the number of effective collisions increases the rate of reactions increases

10

Use collision theory to describe how pressure affects rate of reaction

The higher the pressure in a gaseous reaction the closer together the particles, which leads to an increase in the number of collisions between reactants molecules. This increases the number of collisions with sufficient energy and correct orientation, so increases the rate of reaction

11

Use collision theory to describe how particle size affects rate of reaction

Since particles can only collide with solid on the surface, more surface area in contact with the acid means more collisions per second. More of these collisions will have sufficient energy and in the correct orientation, so smaller particles increases the rate of reaction

12

Use collision theory to describe how temperature affects rate of reaction

Acid particles in a higher temperature beaker are moving faster which leads to an increase in number of collisions with sufficient energy and in the correct orientation which increases the rate of reaction

13

What does increasing the temperature by 10 degrees celcius do to the reaction rate?

It approximately doubles the rate of reaction

14

How do you calculate the relative rate and what are the units?

1/time
s-1

15

What is enthalpy change?

The energy difference between the reactants and the products

16

How do you calculate enthalpy change?

Energy of products - energy of reactants

17

What is an exothermic reaction?

A reaction that releases heat to the surroundings (feels hot)

18

What is an endothermic reaction?

A reaction that takes in heat from the surroundings (feels cold)

19

What is the delta H for an endothermic reaction?

Positive

20

What type of diagram is used to show enthalpy change and what is it called?

Potential energy against reaction progress
Potential energy diagram or reaction profile

21

What is the delta H of an ectothermic reaction?

Negative

22

Describe the diagram used to show enthalpy change for an exothermic reaction

Reactants higher energy than products (both straight lines)
Line increases then decreases

23

Describe the diagram used to show enthalpy change for an endothermic reaction

Reactants lower energy than products (both straight lines)
Like increases then decreases

24

What is the activation energy of a reaction?

The minimum kinetic energy required by colliding particles before a reaction will occur
or:
The minimum energy required by colliding particles to form an activated complex

25

How do you calculate the activation energy of a reaction?

Potential energy of the activated complex - Potential energy of the reactants

26

What is the process from the reactants to the products?

The reactants collide and join together to form an activated complex and then this decomposes to form the products

27

What is the activated complex?

An unstable arrangement of atoms formed at the maximum of the potential energy barrier during a reaction

28

What is a catalyst?

A substance that increases the rate of a reaction but can be recovered unchanged at the end of a reaction

29

What do catalysts provide?

An alternative reaction pathway that has a lower activation energy

30

How do catalysts work?

By reducing the activation energy the catalyst allows more reactant molecules to have an energy greater than the activation energy so increases rate of reaction

31

What is the difference in activation energy between catalysed and non-catalysed reaction?

Activation energy is lower in catalysed reactions than non-catalysed reactions

32

What is the difference in enthalpy change between catalysed and non-catalysed reactions?

Enthalpy change stays the same

33

What is temperature?

A measure of the average kinetic energy of the particles of a substance

34

What type of diagram can be used to show the energy of particles when measuring temperature?

An energy distribution diagram

35

What does the area under the energy distribution distribution diagram represent?

The number of particles

36

How do you find the number of particles with greater than the activation energy?

The area under the curve beyond Ea

37

Describe the number of particles with greater than the activation energy in hot samples compared to cold

The number of particles with greater than the activation energy in a hot sample is greater than in a cold sample

38

Is the rate of reaction faster in hot or cold samples?

Hot

39

When a catalyst is used is the number of particles with greater than the activation energy more or less?

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