Question

Number of moles of fes2 required to produce 20 mol electrons

Answer 1

Answer:

. a 10 ml portion of this solution on treatment with 3 AgNo3 solution results in complete precipitation of Cl- and Br- giving 0.9065 gram of precipitate. the precipitate thus obtained was shaken with a dilute solution of NaBr where all AgCl gets converted into AgBr. mass of the new precipitate was found to be 1.005 g. Determine the % mass of CuCl2 and CuBr2 in the original sample.

Answer 2

Complete Question:

O₂ + FeS₂   -------->  FeO + SO₂

The number of moles of FeS₂ required to produce 20 mol electrons to reduce O₂ in the above reaction is

a) 2

b) 10

c) 10/3

d) 5/3

Answer:

The correct answer is option b) 10.

Explanation:

In the above reaction,

Oxidation number of O in O₂ = 0

Oxidation number of O in FeO = -2

O is being reduced to form FeO.

Here, one mole of FeS₂ is producing 2 electrons (from Fe) or we can say one mole of FeS₂ produces 2 mol electrons.

But to get reduced, O₂ needs 4 electrons. It means 2 moles of FeS₂ reduce O₂ by producing 4 mol electrons.

2 moles of FeS₂ = 4 mol electrons

4 mol electrons = 2 moles of FeS₂

1 mol electrons = 2/4 moles of FeS₂

1 mol electrons = 0.5 moles of FeS₂

Now, we have to find for 20 mol electrons.

∴ 20 mol electrons = (0.5 × 20) moles of FeS₂

20 mol electrons = 10 moles of FeS₂

Hence, 10 moles of FeS₂ are required to produce 20 mol electrons to reduce O₂.

So, option b) is the correct answer.

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