redox

Question 1

How do you balance half equations

Answer 1

1. Balance for the central ion/ atom
2. Balance for the O present by adding water molecules
3. Balance for the H by adding H+ ions
4. Balance for the charge by adding electrons

Question 2

What does an increase in oxidation state show

Answer 2

Oxidation

Question 3

What does a decrease in oxidation state show

Answer 3

Reduction

Question 4

Oxidation is

Answer 4

Loss of electrons

Question 5

Reduction is

Answer 5

Gain of electrons

Question 6

What is an oxidising agent

Answer 6

Accepts electrons

Question 7

What is a reducing agent

Answer 7

Donates electrons

Question 8

An oxidising agent oxidises some other chemical (or species)

Answer 8

It itself is reduced
Gaining E-s from another chemical

Question 9

A reducing agent reduces some other species

Answer 9

It itself is oxidised
Loses E-s to another chemical

Question 10

What are rules for finding oxidation states

Answer 10

• Uncombined elements (e.g. Mg, Na) have an oxidation state
of zero.
• The sum of all the oxidation states in a compound (for example: NaCI) is zero.
• The oxidation state of a simple ion (for example: Mg?+) is equal to its charge.
• The sum of all the oxidation states in a complex ion (for example: NH4*) is equal to its charge.
• Some atoms always (or usually) have the same oxidation state in compounds.

Question 11

What is the phrase for oxidation states

Answer 11

Under; Uncombined elements, Oz is zero

My; Metals, Na is +1, Mg is +2

Face; Fluorine is - 1
Here’s; Hydrogen is +1 (except in metal hydrides, NaH where H is -1)

Our; Oxygen is -2 (except in H202 where O is -1)

Chin; Chlorine is - 1