Module 2.1.5 - Redox

Question 1

What is oxidation number?

Answer 1

The number of electrons that an atom uses to bond with the atoms of another element

Question 2

The sum of all oxidation numbers in a neutral compound is..

Answer 2

0

Question 3

The sum of all the oxidation numbers in an ion is…

Answer 3

equal to the charge on that ion.

Question 4

The oxidation number of any uncombined element is..

Answer 4

0

Question 5

The oxidation number of oxygen in compounds is..

Answer 5

-2 (except in peroxides H2O2, O is -1)

Question 6

The oxidation number of hydrogen in compounds is..

Answer 6

+1 (except in hydrides, bonded to a metal)

Question 7

A group 1 element in an compound has a oxidation number of…

Answer 7

+1

Question 8

A group 2 element in an compound has a oxidation number of…

Answer 8

+2

Question 9

A group 3 element in an compound has a oxidation number of…

Answer 9

+3

Question 10

What is the most electronegative element?

Answer 10

Fluorine (always -1)

Question 11

What do group 7 elements have?

Answer 11

Varying oxidation numbers.
Assume is -1, unless asked to find

Question 12

What do roman numerals represent?

Answer 12

the oxidation state of an element that can exist in more than one oxidation state (typical for transition metals, found in d-block)

Question 13

What are oxyanions?

Answer 13

Negative ions containing oxygen and one or more other elements

Question 14

What do the names of oxyanions normally end in?

Answer 14

‘-ate’

Question 15

What do oxyanions aim for?

Answer 15

Lowest negative charge

Question 16

What is the systematic name?

Answer 16

The word name of the compound, which can have the positive charge in roman numerals

Question 17

What is redox?

Answer 17

A reaction where both oxidation and reduction take place?

Question 18

What is oxidation?

Answer 18

Loss of electrons/an increase in oxidation number

Question 19

What is reduction?

Answer 19

The gain of electrons/a decrease in oxidation number

Question 20

How do you determine whether or not a reaction is redox?

Answer 20

• the changes in oxidation number of an element
• the transfer of electrons to/from an element

Question 21

What does “OIL RIG” stand for?

Answer 21

Oxidation is loss (of electrons), reduction is gain (of electrons)

Question 22

What do metals tend to do to form positive ions?

Answer 22

Lose electrons: undergo oxidation

Question 23

What do non-metals tend to do to form negative ions?

Answer 23

Gain electrons: undergo reduction

Question 24

What is an oxidising agent?

Answer 24

A reagent that oxidises (takes electrons from) another species; is reduced (electron acceptor)

Question 25

What is a reducing agent?

Answer 25

A reagent that reduces (adds electrons to) another species; is oxidised (electron donor)

Question 26

How do you construct a redox equation from half-equations?

Answer 26

Two half-equations must be combined
- multiply the half-equation(s) by a factor so number of electrons in each half-equation are the same
- add the two half-equations together, like pair of simultaneous equations
- electrons should cancel out, leaving redox equation

Question 27

A2 ) How do you construct half-equations

Answer 27

1) Balance the element being oxidised or reduced
2) Balance the oxidation number: use ELECTRONS e-
3) Balance the charge using H+ (acid) or OH- (Alkali)
4) just add water to balance the O and H