oxidation and reduction

Question 1

What is oxidation?

Answer 1

Oxidation is the loss of electrons / gain of oxygen

Question 2

What is reduction?

Answer 2

Reduction is the gain of electrons/loos of oxygen

Question 3

In electrolysis what is a good way of memorizing this?

Answer 3

Anox > oxidation at the anode

Redcat > reduction at the cathode

Question 4

What is the oxidation numbers?

Answer 4

The charge the atom would have if it was composed of ions

>reflects the number of electrons that have been lost/gained

Question 5

What is reduction in terms of oxidation numbers?

Answer 5

A decrease

Question 6

What is oxidation in terms of oxidation numbers?

Answer 6

An increase

Question 7

What do changes in the oxidation numbers reflect?

Answer 7

Whether or not the reaction was oxidation or reduction

Question 8

Worked example :

N2 +3H2->2NH3

Answer 8

N:0(uncombined) in ammonia is combined :x
H:0(uncombined) in ammonia is combined :+1

H=+1
Sum=0
X+(3x1) =0
X+3=0
X=-3
Meaning that the oxidation number in nitrogen in ammonia is -3

Question 9

What happens when metals react with acids?

Answer 9

Metal is oxidized
Hydrogen is reduced to from hydrogen gas
Is redox

Question 10

Example of redox reaction:

2Na+2HCl>2NaCl+H2

Answer 10

First. Second
Sodium: 0. +1. : oxidation
Hydrogen:+1. 0 : reduction

Question 11

What is the role of oxidizing agents?

Answer 11

They oxidize other things and are themselves reduced in order to do so

Question 12

What is the role of reducing agents?

Answer 12

They reduce other things and are themselves oxidized to do so

Question 13

What is a disproportionation reaction?

Answer 13

Reactions where the same element is both reduced and oxidized, we can see the changes through the oxidation number to classify reactions

Question 14

Worked example:
H2O2> H2O +O2

What is occurring in the elements?

Answer 14

Oxygen is being both oxidized:[H2O2>O2]
Start:-1
End:0
Reduced [ H2O2->H2O]
Start:-1
End:-2
So this reaction is being both oxidized and

Question 15

ESQ:Which of the equations below represents a redox reaction?
A: Mg+H2SO4>MgSO4+H2
B:Mg(OH)2 +2HCl>2H2O+MgCl2
C:MgO+2HCl>MgCl2
D:MgCO3+2HCl>CO2+H2O+MgCl2

Answer 15

A: Mg+H2SO4>MgSO4+H2
Mg: 0. +2
H: +1. 0
{OXIDATION IS OCCURING WITH Mg AND REDUCTION WITH H2}
[redox]

Question 16

In terms of electron transfer, what does the term oxidation mean?

Answer 16

Oxidation is the loss of electrons

Question 17

When heated, zinc reacts with calcium carbonate CaCO3, the reaction is a redox reaction:
Zn(s)+CaCO3(s)>ZnO(s) + CaO(s) +CO(g)
Which element has been oxidized and which reduced?

Answer 17

Zn:0
ZnO: rule -2
Sum:0
… x+-2=0
X=2
… Zn:0>2 
Ca: +2
CaCO3: rule:O=-2
Sum:0
Ca=+2
\+2+x+(3x-2)
X+2-6=0
X=4
CO:
Sum:0
X+-2=0
X=+2