Equilibria and Redox Reactions Flashcards Preview

AQA Chemistry Y1 Revision > Equilibria and Redox Reactions > Flashcards

Flashcards in Equilibria and Redox Reactions Deck (34):
1

Explain what is meant by dynamic equilibrium

The forward reaction occurs at the same rate as the backwards reaction.

The concentrations of the products and reactants are constant.

2

What conditions are required for a dynamic equilibrium to be reached?

The reaction must occur in a closed system

The reaction must occur at a constant temperature

3

What was Le Chatelier's principle?

If you change the concentration , pressure or temperature of a reversible reaction , the position of equilibrium will shift to oppose the change.

4

In a reaction at equilibrium if the pressure is increased what will happen?

The equilibrium will shift to the side where there are fewer moles to reduce the pressure, more of the side of the reaction with fewer moles will be produced.

5

In a reaction at equilibrium if the concentration is increased what will happen?

The reaction moves to the side where the species that has not been altered in concentration is on to try and use it up

6

If the FORWARD reaction is exothermic and the temperature is increased what will happen to the position of equilibrium?

The equilibrium will move to the left to absorb the heat

7

What observations can be made as an equilibrium changes place?

colour change providing that the reactants and products are two different colours.

8

Why may compromised conditions be used?

The ideal conditions may be not economically viable
The ideal conditions may require specialist equipment which is expensive
The ideal conditions may be dangerous (very High pressures)
The reaction may be too slow which will not be economically viable

9

What negative effect will using compromised conditions have?

It may reduce the yield of the product

10

What does Kc stand for?

The equilibrium constant

11

What is Kc ?

A ratio worked out from the concentration of products and reactants after equilibrium is reached.

12

when doing Kc calculations what is the units of the numbers used

moldm3 - as your working in concentration

13

If a reaction is exothermic is its energy change positive or negative

negative

14

If a reaction is endothermic is its energy change positive or negative

positive

15

What effect does adding a catalyst have on equilibrium

Catalysts have no effect on the position of equilibrium or the value of Kc , they will however increase the rate of both the forward and backward reaction hence equilibrium is reached more quickly.

16

What is redox reaction?

A redox reaction is a reaction where oxidation and reduction happen simultaneously

17

what does OILRIG stand for ?

Oxidation Is Loss , Reduction Is Gain

18

What is oxidation

Oxidation is a loss of electrons

2+ ----> 3+

19

If something has been oxidised what has been lost ?

Electrons

20

What is an oxidising agent ?

An oxidising agent is something that gains electrons so that other chemical species can loose them and be oxidised.

21

What is reduction?

Reduction is a gain of electrons

22

If something has been reduced what has been gained

Electrons

23

What is a reducing agent?

A reducing agent is something that looses electrons so that others can gain them

24

What is the oxidation state of uncombined elements?

0

25

What is the oxidation state of diatomic molecules?

0

26

What is the sum of the oxidations states of a neutral compound such as HCL

0

27

What would the oxidation state of Iron(II) be ?

+2

28

What would the oxidation state of Iron(III) be ?

+3

29

In peroxides what is the oxidation sate of oxygen

-1

30

What do ionic half equations show?

Oxidation or reduction

31

To combine a reduction equation and a oxidation equation what must be balanced?

The number of electrons.

32

If you add H20 to a redox equation what might you need to add to balance it ?

H+ ions.

33

What is occurring in this reaction

Fe 2+ ----> Fe 3+. + e-

Oxidation

34

What is occurring in this reaction

Fe 3+ + e- -----> Fe2+

Reduction