Redox

Question 1

What are the 4 definitions of oxidation?

Answer 1

1. Gain of oxygen
2. Loss of hydrogen
3. Loss of electron (OIL)* impt
4. INCREASE in oxidation state* impt

Question 2

What are the 4 definitions of reduction?

Answer 2

1. Loss of oxygen
2. Gain of hydrogen
3. Gain of electrons (RIG)* impt
4. DECREASE in oxidation state* impt

Question 3

How to explain increase/decrease in oxidation state?

Answer 3

STATE oxidation state BEFORE and AFTER
eg. Fe is oxidised as OS of Fe increased from 0 in Fe to +2 in FeSO4
CuSO4 is reduced as OS of CU decreases from +2 in CuSO4 to 0 in Cu

Question 4

How to test for reducing agent?

Answer 4

Use Acidified aqueous potassium manganate (VII), KMnO4, is an oxidising agent
KMnO4 turns from purple to colourless,
KMnO4 is decolourised if RA present, itself is reduced

Question 5

How to test for oxidising agent?

Answer 5

Use aqueous potassium iodide KI, is a reducing agent

KI turns colourless to brown if OA is present, itself is oxidised