Rates of reactions + Redox reactions

Question 1

What is a redox reaction?

Answer 1

A reduction and oxidation reaction both happening simultaneously

Question 2

What does OILRIG mean?

Answer 2

• oxidation is loss of electrons

- reduction is the gain of electrons

Question 3

What is the oxidation state of an atom?

Answer 3

• a positive or negative number assigned to an element in a chemical composition which represents the number of electrons lost (or gained, if the number is negative), by an atom of that element in the compound.

Question 4

What is the oxidation state of pure phases/free element e.g. Nitrogen N2 or calcium ca2+?

Answer 4

Zero

Question 5

What is the oxidation number of the ion of an element?

Answer 5

The oxidation of an ion of an element is equal to its charge e.g. Cu 2+ is 2+

Question 6

What is the oxidation number of hydrogen in a molecule?

Answer 6

+1

Question 7

During a chemical reaction, what does an increase in oxidation number signify?

Answer 7

it signifies oxidation

Question 8

During a chemical reaction, what does an decrease in oxidation number signify?

Answer 8

it signifies reduction

Question 9

How is Fe 2+ made into Fe3+?

Answer 9

By an oxidation reaction as the oxidation number has increased so a loss of electron has occurred.

Question 10

What is the state of organic carbon in these terms?

Answer 10

All organic carbon is reduced

Question 11

Describe the redox reactions in respiration

Answer 11

oxidation of organic carbon

reduction of oxygen

Question 12

What 3 things affects the rate of reactions?

Answer 12

• orientation, energy and collisions

Question 13

What is significant of a chemical with a long half life?

Answer 13

more likely to persist and therefore be transported in the environment

Question 14

What must be required in order for an reaction to occur?

Answer 14

a collision of atoms which must have enough energy to overcome the activation energy

Question 15

Define activation energy

Answer 15

The minimum/initial input of energy needed to force the reaction to start

Question 16

What is a half life?

Answer 16

how long it takes to react 50% of reactants of the initial concentration

Question 17

What does k represent in this context?

Answer 17

The rate constant for any given reaction

Question 18

What is the effect of concentration on reaction rates and why?

Answer 18

Increasing the concentration of the reactants increases the rate of reactions because there are more particles which increases the likelihood of collisions

Question 19

What does it mean if the order with respect to A of a reaction is 0?

Answer 19

this means that the concentration of A doesn’t affect the rate of reaction.

Question 20

What are the units for rate of reactions?

Answer 20

mol dm-3 s-1.

Question 21

What is the order of a reaction?

Answer 21

It determines the relationship between the rate of reaction and the concentration of reactants or products

Question 22

Describe the initial state as a reaction begins

Answer 22

• no products yet formed
• high rate of collisions between A+B
• rate of forward reaction