5.5 - Redox and Electrode Potentials

Question 1

What is a loss of electrons called?

Answer 1

Oxidation

Question 2

What is a gain of electrons called?

Answer 2

Reduction

Question 3

What does the term redox show?

Answer 3

Reduction and oxidation are taking place simultaneously

Question 4

What does an oxidising agent do, and what is the outcome?

Answer 4

An oxidising agent accepts electrons, and gets reduced

Question 5

What does a reducing agent do, and what is the outcome?

Answer 5

A reducing agent donates electrons and gets oxidised

Question 6

What does an oxidation half-equation and a reduction half-equation combine together to make?

Answer 6

A full redox equation

Question 7

Why are electrons shown in half-equations?

Answer 7

So that the charges balance

Question 8

What does the oxidation number of an element show?

Answer 8

The total number of electrons that it has donated or accepted

Question 9

What is the trend of oxidation numbers? (When do they go up/down)

Answer 9

Up as electrons are lost, down as they are gained

Question 10

When an electron is lost, what happens to the oxidation number?

Answer 10

It increases by one

Question 11

When an electron is gained, what happens to the oxidation number?

Answer 11

It decreases by one

Question 12

What happens to the oxidation number of an element that is reduced as part of a redox reaction?

Answer 12

It increases by one

Question 13

What happens to the oxidation number of an element that is oxidised as part of a redox reaction?

Answer 13

It decreases

Question 14

What makes transition metal ions good oxidising or reducing agents?

Answer 14

Their ability to gain or lose electrons easily

Question 15

What does transition metal ions’ ability to gain or lose electrons easily mean?

Answer 15

That they are good oxidising or reducing agents

Question 16

How is it easy to spot when transition metals have been oxidised or reduced?

Answer 16

They often change colour

Question 17

What is the colour change that occurs during the redox reaction between Fe²⁺ and manganate (VII) ions? (Include reasons why for both the initial and final colours)

Answer 17

1. Begins purple (due to MnO4^-)
2. Changes to very pale pink/colourless

Question 18

Skip to electrochmical cells (p395), last page was 388

Question 19

What are electrochemical cells made from?

Answer 19

Two different metals dipped in salt solutions of their own ions and connected by a wire (an external circuit)

Question 20

What reactions take place within an electrochemical cell?

Answer 20

Reduction and oxidation

Question 21

What type of process occurs within an electrochemical cell?

Answer 21

Redox

Question 22

Which direction do electrons flow in an electrochmical cell?

Answer 22

From the more reactive metal to the less reactive metal