Chapter 2, Problem 109GQ

(a)

Interpretation Introduction

Interpretation:

For the given set of atoms, the atom having most weight is needed to be calculated.

Concept introduction:

Molar masses of $\text{Na, Si, U, Fe and K are 23g, 28g, 238g, 55}\text{.8g and 39g}$ respectively.

• Conversion formula for mass of an atom into number moles,

    $Numberofmoles=\frac{Massingrams}{Molarmass}$ 

• Equation for finding number of atoms from number of moles of an atom,

    $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Explanation of Solution

Conversion formula for number moles of an atom into mass,

    $Numberofmoles\times Molarmass=Massingrams$

In the given set of atoms, the molar mass of uranium is far greater than remaining atoms.

Hence,

uranium is having more mass among other atoms.

(b)

Interpretation Introduction

Interpretation:

For the given set of atoms, the atom having most weight is needed to be calculated.

Concept introduction:

Molar masses of $\text{Na, Si, U, Fe and K are 23g, 28g, 238g, 55}\text{.8g and 39g}$ respectively.

• Conversion formula for mass of an atom into number moles,

    $Numberofmoles=\frac{Massingrams}{Molarmass}$ 

• Equation for finding number of atoms from number of moles of an atom,

    $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Explanation of Solution

Conversion formula for number moles of an atom into mass,

    $Numberofmoles\times Molarmass=Massingrams$

The molar mass of sodium is $\text{23g}$ ,

The given mass of sodium is $\text{9g}$ .

Conversion formula for mass of an atom into number moles,

Therefore,

  $Numberofmoles=\frac{9g}{23g}=0.4mol$

The given mass of sodium is $1.2\times {10}^{22}$ atoms.

Equation for finding number of atoms from number of moles of an atom,

  $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Therefore,

    $\frac{1.2\times {10}^{22}atoms}{6.022\times {10}^{23}atoms/mol}=0.02mol$

Hence,

The sample of 0.50 mol sodium having more mass among other sodium samples.

(b)

Interpretation Introduction

Interpretation:

For the given set of atoms, the atom having most weight is needed to be calculated.

Concept introduction:

Molar masses of $\text{Na, Si, U, Fe and K are 23g, 28g, 238g, 55}\text{.8g and 39g}$ respectively.

• Conversion formula for mass of an atom into number moles,

    $Numberofmoles=\frac{Massingrams}{Molarmass}$ 

• Equation for finding number of atoms from number of moles of an atom,

    $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Explanation of Solution

Conversion formula for number moles of an atom into mass,

    $Numberofmoles\times Molarmass=Massingrams$

The molar mass of sodium is $\text{23g}$ ,

The given mass of sodium is $\text{9g}$ .

Conversion formula for mass of an atom into number moles,

Therefore,

  $Numberofmoles=\frac{9g}{23g}=0.4mol$

The given mass of sodium is $1.2\times {10}^{22}$ atoms.

Equation for finding number of atoms from number of moles of an atom,

  $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Therefore,

    $\frac{1.2\times {10}^{22}atoms}{6.022\times {10}^{23}atoms/mol}=0.02mol$

Hence,

The sample of 0.50 mol sodium having more mass among other sodium samples.

(c)

Interpretation Introduction

Interpretation:

For the given set of atoms, the atom having most weight is needed to be calculated.

Concept introduction:

Molar masses of $\text{Na, Si, U, Fe and K are 23g, 28g, 238g, 55}\text{.8g and 39g}$ respectively.

• Conversion formula for mass of an atom into number moles,

    $Numberofmoles=\frac{Massingrams}{Molarmass}$ 

• Equation for finding number of atoms from number of moles of an atom,

    $Numberofatoms=numberofmolesofatom\times 6.022\times {10}^{23}atoms/mol$

Explanation of Solution

The given amount of iron and potassium atoms is ten atoms.

Conversion formula for number moles of an atom into mass,

    $Numberofmoles\times Molarmass=Massingrams$

In the given set of atoms, the molar mass of iron is greater than potassium.

The number of moles of $\text{Fe and K}$ are equal.

The molar mass is proportional to the mass of atom.

Hence,

Iron is having more mass as compared to potassium.