Redox 1

Question 1

What is oxidation number?

Answer 1

Valency of an element. Number of electrons necessary to make element neutral.

Question 2

Oxidation number = ?

Answer 2

Charge

Question 3

Oxidation number of oxygen (mostly)

Answer 3

-2

Question 4

Exceptions of oxidation number of oxygen

Answer 4

When with fluorine or in peroxide, -1. In superoxides, -0.5.

Question 5

Oxidation number of fluorine always

Answer 5

-1

Question 6

Oxidation number of hydrogen

Answer 6

1. In hydrides, -1.

Question 7

What is oxidation?

Answer 7

Loss of electrons

Question 8

What is reduction?

Answer 8

Gain of electrons

Question 9

Oxidising agent

Answer 9

Gains electrons, is itself reduced.

Question 10

Reducing agent

Answer 10

Loses electrons, is itself oxidised.

Question 11

What is disproportionation?

Answer 11

Element in a single species being simultaneously reduced and oxidised.

Question 12

Why is oxidation number useful?

Answer 12

Assigning oxidation number to elements allows one to see whether an element has been reduced or oxidised.

Question 13

Which ions do metal form?

Answer 13

Positive ions by loss of electrons, increase in oxidation number.

Question 14

Which ions do non-metals form?

Answer 14

Negative ions by gain of electrons, decrease in oxidation number.

Question 15

What colour is iron (II) and what colour is iron (III)?

Answer 15

Pale green and pale yellow.

Question 16

What colour is MnO4- and what colour is Mn2+?

Answer 16

Deep purple and colourless.

Question 17

What to add and when to I2/S2O3 2- titration?

Answer 17

Add starch near the end, blue black to colourless.