4.4c Recognizing Oxidation-Reduction Reactions

Oxidation-reduction reactions always involve a change in the?

Oxidation number of one or more atoms

If any of the oxidation numbers change when proceeding from reactants to products, the reaction is an?

Oxidation-Reduction reaction

Assign oxidation numbers for all atoms in this reaction
Cl2(g)+H3AsO4(aq)-->HAsO2(aq)+2HClO(aq)

Cl2= 0
H3=+1
As=+5
O4=-2
H=+1
As=+3
O2=-2
H=+1
Cl=+1
O=-2

Any element with a change in oxidation number when proceeding from reactants to products has been?

Oxidized or reduced

Cl2(g)+H3AsO4(aq)-->HAsO2(aq)+2HClO(aq)
the oxidation number of chlorine increases from 0 (in Cl2) to?
The oxidation number has increased because?

- +1 in HClO
- Each chlorine atom has lost an electron

Cl2(g)+H3AsO4(aq)-->HAsO2(aq)+2HClO(aq)
In this reaction, has Cl2 been oxidized or reduced? The oxidizing or reducing agent?

Oxidized so it is the reducing agent

Cl2(g)+H3AsO4(aq)-->HAsO2(aq)+2HClO(aq)
In this reaction, the oxidation # of arsenic decreases from +5 in H2AsO4 to?
The oxidation number has decreased because?

- +3 is HAsO2
- Each arsenic atom has gained two electrons

Cl2(g)+H3AsO4(aq)-->HAsO2(aq)+2HClO(aq)
In this reaction, has H3AsO4 been oxidized or reduced? The oxidizing or reducing agent?

It has been reduced and is the oxidizing agent

Oxidation-reduction reactions often involve?

One or more common oxidizing and reducing agents

When O2 is the oxidizing agent what is usually the reaction product?

O2- (oxide ion) or an oxygen containing molecular compound

When H2O2 is the oxidizing agent what is usually the reaction product?

H2O(l)

When F2, Cl2, Br2, or I2 are the oxidizing agent what is usually the reaction product?

F-, Cl-, Br-, or I- (the halide ions)

When Cr2O7 2- (dichromate ion) is the oxidizing agent what is usually the reaction product?

Cr 3+ (chromium (III) ions in acidic solution

When MnO4- (permanganate ion) is the oxidizing agent what is usually the reaction product?

Mn 2+ (manganese (II) ion in acid solution

When H2 (hydrogen) or hydrogen containing molecular compounds is the reducing agent what is usually the reaction product?

H+ (hydrogen ion) or H combined in H2O

When C (carbon) used to reduce metals oxides is the reducing agent what is usually the reaction product?

CO and CO2

When M, metals such as Na K Fe or Al is the reducing agent what is usually the reaction product?

M+, metal ions such as Na+ K+ Fe3+ or Al 3+

Reactions involving a pure element are usually?

Oxidation-reduction reactions

Almost all reactions involving compounds with atoms in very high or very low oxidation states are?

Oxidation reduction reactions

Mn has a very high oxidation number of ____ in the permanganate ion (MnO4-).

+7

The permanganate ion is a strong oxidizing agent because?

Reactions involving the ion almost always involve it being reduced to a lower oxidation number.

All combustion reactions and most explosive reactions are?

Oxidation-reduction reactions

In reactions that involve the burning of organic matter in air, which is the reducing agent and which is always the oxidizing agent?

The organic material is the reducing agent and O2 in air is the oxidizing agent

Identify the oxidizing agent and the reducing agent in the following reaction
Mn(s) + 2HCl(aq)--> MnCl2(aq) + H2(g)

Mn is the reducing agent
HCl is the oxidizing agent

Identify the oxidizing agent and the reducing agent in the following reaction
Sn(s) + Br2(l)--->Sn2+(aq) + 2Br-(aq)

Sn is the reducing agent
Br2 is the oxidizing agent