how to find redox reaction
Answers
Answer:
Explanation:
Oxidation numbers are a convenient way of identifying redox reactions and also indicating which element is oxidized and which is reduced. Here's an example - the reaction between sodium metal and chlorine gas:
2Na+Cl2⟶2NaCl
It is often useful to write the oxidation number for every element, in every compound, above the element in the equation. Thus for our reaction we have:
Be sure to note that the balancing coefficients in the equation (the "2" in front of Na and in front of NaCl ) do not affect the value of the oxidation numbers. We'll return to these coefficients soon.
A chart is a useful way for us to summarize the changes in oxidation number for each element:
element
initial
ox no
final
ox no
change in
electrons (e-)
oxidized or
reduced
Na
0
→
+1
lost 1 e-
oxidized
Cl
0
→
-1
gain 1 e-
reduced
We see several important things in our table
Since oxidation numbers did change, this was a redox reaction
Na 's oxidation number increased - from 0 on the reactant side to +1 on the product side. An element becomes more positive by losing electrons.
Loss of electrons is Oxidation (LEO)
Cl 's oxidation number decreased, from 0 to -1, as chlorine gained electrons.
Gain of electrons is Reduction (GER)
An increase in oxidation number indicates oxidation
A decrease in oxidation number indicates reduction
Let's try another example. Identifying what is oxidized and what is reduced - and how many electrons are involved - is very important to master now for we will expand upon this skill shortly.
Consider the reaction
2Mg+O2⟶2MgO
Determine oxidation numbers for all elements in every compound:
0 0 +1 -2
2Mg+O2⟶2MgO
Summarize the changes, determine the number of electrons transferred per atom, and identify what is oxidized and what is reduced:
element
initial
ox no
final
ox no
change in
electrons (e-)
oxidized or
reduced
Mg
0
→
+2
lost 2e-
oxidized
O
0
→
-2
gain 2e-
reduced
Two new terms before we continue. You will recall that we mentioned in the first section of this unit that oxidation cannot occur without reduction, and vice versa. The substance losing electrons (undergoing oxidation) gives its electrons to the substance gaining electrons (undergoing reduction). If the reduced substance will not accept electrons, the oxidized substance could not give away electrons. Thus, one allows for the other to occur.
Reducing agent
the substance that is oxidized.
It allows another element to be reduced.
Oxidizing agent
the substance that is reduced.
It allows another element to be oxidized.
In our last example above, magnesium was oxidized, therefore it was the reducing agent. Oxygen was reduced, therefore it was the oxidizing agent.
By convention we often refer to the oxidizing agent and reducing agents as the entire compound the element is in, not just individual element. Consider the following reaction. Oxidation numbers are shown only for substances whose oxidation numbers undergo a change:
0 +5(N) +2(Zn) +4(N)
Zn+HNO3⟶Zn(NO3)2+NO2+H2O
Summarize:
element
initial
ox no
final
ox no
e-
oxidized or
reduced
Agent
Zn
0
→
+2
lost 2e-
oxidized
reducing agent:
Zn
N
+5
→
+4
gain 1e-
reduced
oxidizing agent:
HNO3
We see that HNO3 is referred to as the oxidizing agent, not just N.
One final thing to note in this example - notice that the nitrogen in Zn(NO3)2 did not undergo a change in oxidation number.
Here is a final example.
Consider the reaction
N2+2H2⟶2NH3
Determine oxidation numbers for all elements in every compound:
0 0 -3 +1
N2+2H2⟶2NH3
Summarize the changes, determine the number of electrons transferred per atom, and identify what is oxidized and what is reduced, and identify the oxidizing agent and reducing agent:
element
initial
ox no
final
ox no
e-
oxidized or
reduced
Agent
N
0
→
-3
gain 3e-
reduced
oxidizing agent: N2
H
0
→
+1
lose 1e-
oxidized
reducing agent: H2
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1.2: Oxidation Numbers 1.4 Balancing Redox Reactions Using Oxidation Numbers
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Explanation:
redox reactions are the type of reactions which include both oxidization as well as reduction. so if a reaction have both reducting agents and oxidizing agent then the reaction is redox reaction