1. What is the oxidation number of the sulfur atom in Na 2 SO 4 ? So i know the

Question

1. What is the oxidation number of the sulfur atom in Na 2 SO 4 ?

So i know the answer is +6, guess my question is why? or how? can someone explain?

2. Which species functions as the oxidizing agent in the following reduction-oxidation reaction:   5 Fe2+(aq) + MnO4 -(aq) + 8 H+(aq) ? Mn2+(aq) + 5 Fe3+(aq) + 4 H2O(l)?

The answer for this is : MnO4- (aq). So can somone explain to me how this came to be the answer, or why?

3. What is the oxidation number change for the iron atom in the reaction:   2 Fe2O3(s) + 3 C(s) ? 4 Fe(s) + 3 CO2(g)?

answer is -3, but why though??

I guess im having problems with oxidation number changes in reactions..

4. Which species functions as the reducing agent in the following reduction-oxidation reaction: 2 P(s) + 3 Br2(l) ? 2 PBr3(l)?

Answer is : P(s) but how or why??? I am so confuse someone please explain!!!

Explanation / Answer

1. We can easily calculate the oxidation number of any element in a compound by following simple rules.for example the oxidation number of alkali metals is +1 , oxidn no of Oxygen is -2 in all cases accept with flouride

And the total oxidation number of compound is equal to the charge on the compound

In this case Na2SO4

2(+1) + S + 4(-2) = 0, on equating S= 6

Therefore oxidn number of sulphur = +6

2. The species in which there is a decrease in oxidation number of main element , that species ac as oxidising agent, as it is accepting electron and making other less in number of electron.

Here the oxidation state of Mn in KMnO4 is +7

While in Mn+2 , the state is obviously +2

So it is oxising agent

3.in Fe2O3 the oxidation number of iron can be calculated as

2X Fe +3(-2) = 0 ( as mentioned in step 1)

So Fe = +3

While in Fe(s) the oxidation state is 0 (in pure state the oxidation state of element is 0). So the change is -3

4. Now the reducing agent is the species which undergo increase in oxidation state of main element.

Here phosphorous changes from 0 (pure element) to +3. It lises electrons which ate gained by other(Br).

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.