Chapter 14, Problem 9STP

Interpretation Introduction

Interpretation:

The correct statement have to befound.

Concept introduction:

Mole: The mole is the unit which is used to measure the amount of a substance. A mole can be defined as the number of carbon atoms which is present in exactly 12 g of pure carbon-12. A mole contains 6.023 × 10²³ particles.

Stoichiometry: It can be defined as a study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction.

Answer to Problem 9STP

Answer is B. 2 moles of hydrogen gas will be left over.

Explanation of Solution

${\mathrm{Fe}}_3{O}_4(s)+4H_2(g)\to 3Fe(s)+4H_{2}O(l)$

From the above balanced chemical equation, you can say that one mole of iron(III) oxide reacts with four moles of hydrogen to produce three moles of iron and four moles of water.

One mole of iron(III) oxide reacts with four moles of hydrogen

So, 7 moles of iron(III) oxide will react with = $\frac{7molF{e}_3{O}_4\times 4mol{H}_2}{1molF{e}_3{O}_4}=28mol{H}_2$

So, in the given data, 30 moles of hydrogen gas is mixed with the iron oxide but 28 moles of hydrogen is required for the reaction. So, (30 - 28) = 2 moles of hydrogen gas will be left over. The correct answer is B.

Conclusion

Reasons for incorrect options:

As, we see from the calculation 28 moles of hydrogen is required for the reaction.

7 moles of iron(III) oxide will react with = $\frac{7molF{e}_3{O}_4\times 4mol{H}_2}{1molF{e}_3{O}_4}=28mol{H}_2$

So, in the given data, 30 moles of hydrogen gas is mixed with the iron oxide but 28 moles of hydrogen is required for the reaction. So, (30 - 28) = 2 moles of hydrogen gas will be left over. The correct answer is B.

That means other options that is,

A. There will be no reactants left.

C. 30 moles of water will be produced

D. 7 moles of Fe will be produced are found to be incorrect.