7.0 Oxidation, reduction, and redox reactions

Question 1

What is oxidation in terms of oxygen?

Answer 1

The gain of oxygen

Question 2

What is oxidation in terms of electrons?

Answer 2

The loss of electrons

Question 3

What does an oxidising agent do?

Answer 3

Donate oxygen/accept electrons (it is reduced)

Question 4

What is reduction in terms of oxygen?

Answer 4

The loss of oxygen

Question 5

What is reduction in terms of electrons?

Answer 5

The gain of electrons

Question 6

What does a reducing agent do?

Answer 6

Accept oxygen/donate electrons (it is oxidised)

Question 7

What are redox reactions?

Answer 7

Reactions in which both oxidation and reduction occur

Question 8

What are used to see what has been oxidised and
what has been reduced in a redox reaction?

Answer 8

Oxidation states or oxidation numbers

Question 9

What is the oxidation state for an element?

Answer 9

Zero

Question 10

What is the oxidation state of a metal in its
compound?

Answer 10

The charge on the ion that it forms

Question 11

What is the oxidation state of a hydrogen, H atom in a compound?

Answer 11

It is +1 unless in a hydride e.g. NaH, where it is -1

Question 12

What is the oxidation state of an oxygen, O atom in a compound?

Answer 12

It is -2 unless it is in a peroxide e.g. H2O2 and compounds with F, where it is -1

Question 13

What is the oxidation state of chlorine, Cl atom in a
compound?

Answer 13

It is -1 unless when bonded to F and O, where it can have positive values

Question 14

What is disproportionation?

Answer 14

A redox reaction in which the oxidation state of some atoms of a particular element increases in oxidation state and of others decrease in oxidation state

Question 15

What are the 5 rules for constructing a balanced half
equation for compounds that contain oxygen?

Answer 15

1. Write down the reactants and products and
   balance any non-oxygen atoms that appear on
   both sides of the equation
2. Balance oxygen atoms with water (H2O)
3. 4. 5. molecules
         Balance hydrogen atoms with hydrogen ions (H+).
         Balance the charges with electrons
         Check the equation balances using the charges
         and oxidation states

Question 16

What are the 3 rules for constructing a balanced redox equation?

Answer 16

1. Construct both half-equations
2. 3. Make sure that the number of electrons in each
      half equation are the same, so that the electrons
      cancel out
      Add the half-equations and cancel the electrons
      and other species that appear on both sides of
      the equation

Question 17

What are the 3 rules for constructing half-equations
from a balanced redox equation?

Answer 17

1. 2. 3. Write the oxidation state above each element in
         the balanced redox equation
         Use the oxidation states to identify what
         reactants have been oxidised and reduced
         Construct the half-equations for these identified
         reactants