Redox Reactions 1

Question 1

What is oxidation ?

Answer 1

The loss of electrons
It involves an increase in oxidation number

Question 2

What is reduction ?

Answer 2

The gain of electrons
It involves a decrease in oxidation number

Question 3

How to balance half equations?

Answer 3

Mass
Oxygen (H20)
Hydrogen (H+)
Electrons

Question 4

Rules for assigning oxidation numbers

Answer 4

1. All uncombined elements have oxidation number of zero
2. The oxidation numbers of the elements in a compound add up to zero
3. The oxidation numbers of a monoatomic ion is equal to the ionic charge
   Group one metals= +1
   Group two metals = +2
   Al= +3
   H= +1 but in hydrides= -1 eg. NaH
   Cl, Br, I= -1
   O= -2 but in peroxides= -1

Question 5

Where are the electrons in a reduction half equation?

Answer 5

Left

Question 6

What is a reducing agent ?

Answer 6

Electron donor

Question 7

What is an oxidising agent ?

Answer 7

Electron acceptor

Question 8

What takes place at the anode ?

Answer 8

Oxidation
+ve charged but attracts negative ions

Question 9

What takes place at the cathode ?

Answer 9

Reduction
-ve charged but attracts +ve ions

Question 10

What are the standard conditions of a hydrogen electrode ?

Answer 10

1. 25°c
2. 1mol/L conc of hydrogen
3. 1013hPa