1.7 Redox

Question 1

what is meant by oxidation?

Answer 1

• loss of electrons
• increase in oxidation number

Question 2

what is meant by reduction?

Answer 2

• electron gain
• a decrease in oxidation number

Question 3

what is the rule for all uncombined elements?

Answer 3

• they have an oxidation number of zero

Question 4

what is the rule for the sum of oxidation numbers in a compound?

Answer 4

• the oxidation numbers add up to zero

Question 5

what is the rule for the oxidation number of an ion?

Answer 5

• the oxidation number of a monoatomic ion is equal to the ionic charge

Question 6

what is the rule for the oxidation number of a polyatomic ion?

Answer 6

• the sum of the individual oxidation numbers of the elements adds up to the charge on the ion

Question 7

what is the oxidation number of Fe in FeCl3

Answer 7

3+

Question 8

what is meant by a reducing agent?

Answer 8

• electron donors

Question 9

what is meant by an oxidising agent?

Answer 9

• electron acceptors

Question 10

what should you remember when naming oxidising and reducing agents?

Answer 10

• always refer to the full name of the substance

Question 11

how would i write the half equation for :

MnO4- > Mn2+

Answer 11

• balance the change in O.N with electrons
• add H2O to balance the O’s in MnO4^-
• add H+ in reactants to balance H’s in H2O

Question 12

how would you combine the two half equations

Answer 12

• there must be an equal number of electrons in the two half equations so that the electrons cancel out