Redox

Question 1

What is a redox reaction?

Answer 1

A redox reaction is one where oxidation and reduction occurs simultaneously in a complementary manner. In redox reaction, one reactant/substance is oxidised and another is reduced. The reactant/substance that is oxidised is called the reducing agent while the reactant/substance that is reduced is called the oxidising agent.

Question 2

What is the meaning of a reducing agent?

Answer 2

The reactant/substance that is oxidised is called the reducing agent.

Question 3

What is the meaning of an oxidising agent?

Answer 3

The reactant/substance that is reduced is called the oxidising agent.

Question 4

How many definition of oxidation-reduction are there?

Answer 4

There are four definitions of oxidation-reduction, but our focus is only on two of the more important definitions.

Question 5

What is the meaning of inductive reasoning?

Answer 5

Inductive reasoning is the process by which a generalisation is arrived at after examining specific examples.

Question 6

A reactant/substance is oxidised when ___________.

Answer 6

it loses electrons

Question 7

A reactant/substance is reduced when ___________.

Answer 7

it gains electron

Question 8

Reactions involving a transfer of electrons can be viewed as ________.

one half equation shows ______ while the other half equation shows ______.

This is also known as ______.

Answer 8

Can be viewed as two halves

One half equation shows oxidation while the other half equation shows reduction

This is also known as half equations

Question 9

What is oxidation state or oxidation number?

Answer 9

The oxidation state or oxidation number is an artificial construct invented by chemists to help them understand redox reaction better.

It is a number given to an element. This number is preceded by a “+” or a “-“ sign. In general, this number is the charge the atom of the element would have if it exists as an ion in a compound (even if the compound is actually a covalent compound

Question 10

What is the second definition of redox?

Answer 10

Definition 2: defining Redox in terms of Oxidation Number/State

An element is oxidised when its oxidation number increases.

An element is reduced when its oxidised number decreases.

Question 11

Elements that are uncombined with other elements is assigned an oxidation number of _____

Answer 11

zero

Question 12

In simple ions, the oxidation number is simply the ______ on the ion.

Answer 12

Charge

Question 13

In polyatomic ions, the sum of the oxidation numbers ________

Answer 13

Equals the charge on the ion

Question 14

The oxidation number of hydrogen in all its compounds is ____, except in metal hydrides where its oxidation number is ______.

Answer 14

The oxidation number of hydrogen in all its compounds is +1, except in metal hydrides where its oxidation number is -1

Question 15

The oxidation number of oxygen in all its compounds is _____, except in peroxides where its oxidation number is ____.

Answer 15

First blank: -2
Second blank: - 1

Question 16

The oxidation number of group 1 elements (e.g. sodium) in their compounds is ____, for group 2 elements (e.g. magnesium) in their compounds is ____, and for aluminium in its compounds is _______

Answer 16

First blank: + 1
Second blank: + 2
Third blank: + 3

Question 17

There are many oxidation numbers for group 17 elements in their compounds but the usual one is ____.

Answer 17

-1

Question 18

The ____ of the oxidation numbers of all the ______ in a molecule or a compound is ____

Answer 18

First blank: sum
Second blank: elements
Third blank: zero

Question 19

How do you answer this kind of question?

Explain, using oxidation states, why the reaction is a redox reaction.

Answer 19

The oxidation state of (element) increased/decreased from (number) in (reactant) to (number) in product. Hence (reactant) is reduced.

Question 20

How should you answer this kind of question: Using electron transfer, explain why the following reaction is a redox reaction?

Answer 20

So you need to use the half equation concept here

You can write out the half equation and explain:

(Element) loses/gains (electron, specify how many electrons) to become (element/ion) in product. Hence (reactant) is oxidised/reduced to …

Question 21

How you should you answer this question “Which is the reducing agent in the following reaction, explain using oxidation number.”

Answer 21

(Reactant) is the reducing agent. The oxidation number of (reactant) increases/decreases from (number) in (reactant) to (number) in (product). Hence, (reactant) is being oxidised, and therefore, (reactant) is the reducing agent.