Oxidation, reduction and redox reactions

Question 1

oxidation

Answer 1

loss of electrons

Question 2

oxidising agent

Answer 2

electron acceptor (reduced)

Question 3

reduction

Answer 3

gain of electrons

Question 4

reducing agent

Answer 4

electron donor (oxidised)

Question 5

oxidation state

Answer 5

charge an atom of a molecule would have if it were an ion

Question 6

oxidation state rules

Answer 6

• Simple ions have oxidation state same as charge (Cu2+ = Cu +2)
• Elements oxidation state = 0
• Total oxidation states equal overall charge of species
• More electronegative element is assumed to be the negative ion (NaH = Na +1, H -1)
• Range of oxidation state limited by position on periodic table (P is in group 5 = -3 -> +5)

Question 7

redox reaction

Answer 7

where one species is oxidised and another is reduced so both oxidation and reduction takes place

Question 8

disproportionation reaction

Answer 8

a species is simultaneously oxidised and reduced in the same chemical reaction

Question 9

half equation steps

Answer 9

1. Calculate the oxidation state if the element
2. Balance the element (this changes the oxidation state)
3. If oxidation state becomes more negative then add e- on the right
4. Balance out oxygen by adding H2O on the other side
5. Balance out the hydrogen by adding H+ on the other side of the H2O
6. H+ + e- + XO X + H2O

Question 10

combining half equations

Answer 10

1. Treat like a simultaneous equation and balance the e- by multiplying equations
2. Combine the equations and remove the electrons as they cancel out