Chapter 14, Problem 10STP

Interpretation Introduction

Interpretation:

From the given choices, the molar mass of ${\mathrm{Fe}}_3{O}_4$ needs to be identified.

Concept introduction:

Molar mass:

Molar mass is also called molecular weight. It is the sum of mass of all the atoms that makes a particular molecule. Its unit is gram per mole that is g/mol.

If a molecule is

${\mathrm{A}}_X{B}_Y$, the molar mass can be calculated as,

= $\mathrm{Atomic}massofA\times x(numberofatomsofA)+AtomicmassofB\times y(numberofatomsofB)$

Answer to Problem 10STP

Molar mass of ${\mathrm{Fe}}_3{O}_4$ is 231.56 g/mol.

Molar mass is sum of mass of all the atoms that makes a particular molecule.

If a molecule is

${\mathrm{A}}_X{B}_Y$, the molar mass can be calculated as,

= $\mathrm{Atomic}massofA\times x(numberofatomsofA)+AtomicmassofB\times y(numberofatomsofB)$

For

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(AtomicmassofFe\times 3)+(AtomicmassofO\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(55.847\times 3)+(15.99\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

Reasons for incorrect options:

As it can be seen that molar mass of ${\mathrm{Fe}}_3{O}_4$ calculated using the equation:

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(AtomicmassofFe\times 3)+(AtomicmassofO\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(55.847\times 3)+(15.99\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

So, the value calculated is 231.56g/mol

So, the other options which are

b. 71.85 g/mol

c. 287.40 g/mol

d. 215.56 g/mol

Thus, all mentioned above options are incorrect.

Explanation of Solution

Molar mass is sum of mass of all the atoms that makes a particular molecule.

If a molecule is

${\mathrm{A}}_X{B}_Y$, the molar mass can be calculated as,

= $\mathrm{Atomic}massofA\times x(numberofatomsofA)+AtomicmassofB\times y(numberofatomsofB)$

For

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(AtomicmassofFe\times 3)+(AtomicmassofO\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(55.847\times 3)+(15.99\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

Conclusion

Reasons for incorrect options:

As it can be seen that molar mass of ${\mathrm{Fe}}_3{O}_4$ calculated using the equation:

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(AtomicmassofFe\times 3)+(AtomicmassofO\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=(55.847\times 3)+(15.99\times 4)$

$\mathrm{Molar}massofF{e}_3{O}_4^{}=231.547g/mol$

So, the value calculated is 231.56g/mol

So, the other options which are

b. 71.85 g/mol

c. 287.40 g/mol

d. 215.56 g/mol

Thus, all mentioned above options are incorrect.