oxidation and reduction

Question 1

define oxidation in terms of oxidation number

Answer 1

oxidation number increases

Question 2

define reduction in terms of oxidation number

Answer 2

oxidation number decreases

Question 3

define oxidation in terms of electrons

Answer 3

loss of electrons

Question 4

define reduction in terms of electrons

Answer 4

gain of electrons

Question 5

what is an oxidising agent

Answer 5

a substance that brings about oxidation in other substances. the oxidising agent itself is reduced

Question 6

what is a reducing reagent

Answer 6

a substance that brings about reduction in other substances. the reducing agent itself is oxidised

Question 7

what are examples of oxidising agents

Answer 7

hydrogen peroxide
potassium permanganate
sodium hypochlorite in bleach

Question 8

what are examples of reducing agents

Answer 8

sulphur dioxide
carbon monoxide

Question 9

define oxidation number

Answer 9

the charge that an atom has or appears to have when electrons are distributed according to certain rules

Question 10

how do electronegativity values help us to identify oxidation number

Answer 10

the more electronegative element will always have a negative ON

Question 11

what is the oxidation number of any uncombines element eg H2 or O2

Answer 11

0

Question 12

what is the ON of an ion

Answer 12

the same as its charge

Question 13

how do we calculate the ON of a compound?

Answer 13

the ONs of the separate elements must equal 0 when added together

Question 14

what is oxygens ON

Answer 14

-2

Question 15

when is oxygens ON not -2

Answer 15

in peroxides ie H2O2 - (ON= -1)
in OF2 - (ON= +2)

Question 16

what is the ON of halogens

Answer 16

-1

Question 17

when is the ON of halogens not -1

Answer 17

if they are bonded to a more electronegative element

Question 18

how do you identify the oxidising/reducing agent

Answer 18

when an element is reduced the oxidation number decreases
when an element is oxidised the ON is increased
the reducing agent itself is oxidised
the oxidising agent itself is reduced
ie the element that is reduced is the oxidising agent and visa versa

Question 19

how do you balance a redox equation.

Answer 19

assign oxidation numbers to every single element

identify which element change in oxidation number

write the half equations to explain what is happening in step 2

balance the half equations

recombine the half equations into the main equation

balance the rest of the equation

Question 20

how to identify a redox equation

Answer 20

if there are ions in the equation.