redox

Question 1

rules for redox

Answer 1

sum of all ox no in a neutral compound is 0
sum of ox no in an ions is equal to the charge of the ion
th ox no of any uncombined element is 0
the ox no of oxygen is always -2 expect peroxides or when combined with F
the ox no of H is always +1 except hydride when -1
in a compound group 1= ox no of +1
group2=+2
group 3= +3
group 7 can have all different ox no but assume -1 unless asked to find it

Question 2

what is a redox reaction

Answer 2

When both Ox and reduc happen
ox= loss of electron or increase of ox no
reduc= gain of electrons or decrease of ox no
metals tend to be ox and non metals tend to reduc

Question 3

Oxidising agent

Answer 3

is a reagent that oxidises (takes electrons from) another species

Question 4

reducing agent

Answer 4

is a reagent that reduces (adds electrons too) another species

Question 5

Oxidation

Answer 5

is the loss of electrons/increase in oxidation number

Question 6

reduction

Answer 6

reduction is the gain of electrons/ the decrease in oxidation number

Question 7

electron transfer

Answer 7

oxidation is loss
reduction is gain

metals tend to lose- oxidation
non metals tend to gain- reduction

for a reaction to be redox there must be reduction and oxidation so something must lose electrons and something must gain

Question 8

constructing a redox equation from half equations

Answer 8

First × the half equations by a factor so that the number of electrons in both are the same

next add the 2 equations together

then cancel out hydrogen or water

Question 9

constructing half equations

Answer 9

1) balance the elements being oxidised/reduced
2)balance the oxidation numbers:use electrons
3)balance charge using H+ if acid or OH- is alkali
4) add water to balance out H and Os