1.7 Redox

Question 1

Define oxidation and reduction reactions in terms of electrons.

Answer 1

OIL RIG

Question 2

Define reducing agent

Answer 2

A species that donates electrons

Question 3

Define oxidising agent

Answer 3

A species that accepts electrons

Question 4

What do oxidation numbers show?

Answer 4

How oxidised/reduced a substance is

Question 5

Define an oxidation state

Answer 5

The number of electrons lost or gained by an atom in a compound which is given as a charge

Question 6

Define a redox reaction

Answer 6

A reaction where oxidation and reduction happen simultaneously

Question 7

What is a disproportionation reaction?

Answer 7

Simultaneous oxidation and reduction of the same species

Question 8

Describe the rules for assigning oxidation states

Answer 8

-Elements=0
-Simple ions ON= charge on ion
-Oxygen in compound ON= 2- UNLESS IN PEROXIDE then 1-
-Sum of ON’s in compound= 0
-Polyatomic ions sum of ON’s = charge on ion
-Hydrogen in a compound is always 1+ UNLESS IN METAL HYDRIDE them 1-
-if compound has 2 electronegative elements then most electronegative element takes the -ve ON

Question 9

How to write half equations:

Answer 9

-Find out which element is changing state and balance if necessary
-Work out oxidation states of this element
-Balance using electrons
-Balance oxygens using water
-Balance hydrogens using hydrogen ions

Question 10

Making redox equations from balanced half equations:

Answer 10

-Write the 2 half equations
-[R] and [O] half equations should have same number of electrons
-if not multiply so they contains same number of electrons
-add half equations together
-cancel down any of same species either side of arrow