redox

Question 1

What does it mean to be oxidised?

Answer 1

Gain of oxygen, loss of hydrogen, loss of electrons

Question 2

What does it mean to be reduced?

Answer 2

Loss of oxygen, gain of hydrogen, gain of electrons

Question 3

What is a reducing agent?

Answer 3

Allows something else to be reduced

Question 4

What is an oxidising agent?

Answer 4

Allows something else to be oxidised

Question 5

What is an oxidation state?

Answer 5

Represents the total number of electrons that have either been accepted or removed from an element to get to its current form

Question 6

What is the oxidation state of:
oxygen in compounds, except peroxides
oxygen in peroxides
hydrogen in compounds, except metal hydrides
hydrogen in metal hydrides
group 1 metals in coompounds
group 2 metals in compounds
?

Answer 6

-2
-1
+1
-1
+1
+2

Question 7

What are the 7 rules to assign oxidation states?

Answer 7

1. Uncombined elements (not in compounds have an oxidation state of 0
2. In a binary compound, one element always has a positive oxidation state and the other has a negative oxidation state
3. Metals always have positive oxidation states
4. For simple ions, the oxidation state is the charge on the ion
5. The more electronegative element is assumed to take the electrons in the covalent bond and then the compound is treated like an ionic compound
6. The sum of the oxidation states in a compound is always 0
7. The sum of the oxidation states of the atoms in a complex ion is the charge on the ion

Question 8

What are metals?

Answer 8

Reducing agents - they are electron donors

Question 9

What are non metals?

Answer 9

Oxidising agent - electron acceptors

Question 10

What is the oxidising agent when two non metals react?

Answer 10

The more electronegative element

Question 11

What are the 3 rules for constructing half equations?

Answer 11

1. only one element in a half equation changes oxidation state
2. The half equation must balance in terms of atoms
3. The half equation must balance in terms of charge (electrons)