Oxidation and Reduction [C]

Question 1

What does the acronym “OIL RIG” stand for?

Answer 1

Oxidation Is Losing (of electrons)
Reduction is Gaining (of electrons)

Question 2

What is a Redox reaction?

Answer 2

A reaction where transfer of electrons occur.

Question 3

What does a half-equation show?

Answer 3

It shows the loss or gain of electrons.

Mg -> Mg[2+] + 2e

The magnesium gains 2 electrons.

Question 4

What is an “Oxidation State”?

What is the rule for molecules?

Answer 4

A positive or negative number assigned to a compound depending on the amount of electrons lost or gained.

In a molecule, the state must always be 0.

Question 5

How can you work out the oxidation state of the named element in a compound?

Answer 5

Find out the overall oxidation state of the other elements, the named element’s oxidation must equal the number that would make the overall state 0.

For example if we are trying to find O in CO2 and we know the overall state of all other elements equal 5, then oxygen must be -5 to make the overall state 0.

Question 6

Why are transition metals useful?

Answer 6

They have a variable oxidation state.

Question 7

When can a compound not have an overall oxidation state of 0?

Answer 7

If the compound has a preferred charge.

For example SO(4) -2
Has a preferred charge of -2
As oxygen has an oxidation state of -2, we do -2 x 4 = -8
Sulfur must be +6 because that leaves us with the preferred charge of -2