Chapter 6, Problem 15A

(a)

Interpretation Introduction

Interpretation:

The mass of the lithium in grams is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of lithium in $0.251\text{mol}$ is $1.7422\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of lithium is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $0.251\text{mol}$

The molecular mass of lithium = $6.941\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=0.251\text{mol}\times \text{6}\text{.941}\text{g}/\text{mol}\\ =1.7422\text{g}\end{array}$

(b)

Interpretation Introduction

Interpretation:

The mass of the aluminum present in $1.51\text{mol}$ is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of aluminum in $1.51\text{mol}$ is $40.7398\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of aluminum is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $1.51\text{mol}$

The molecular mass of aluminum = $26.98\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=1.51\text{mol}\times \text{26}\text{.98}\text{g}/\text{mol}\\ =40.7398\text{g}\end{array}$

(c)

Interpretation Introduction

Interpretation:

The mass of lead in grams is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of lead in $0.0785\text{mol}$ is $18.13\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of lead is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $8.75\times {10}^{-2}\text{or}0.0875\text{mol}$

The molecular mass of lead = $207.2\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=0.0875\text{mol}\times \text{207}\text{.2}\text{g}/\text{mol}\\ =18.13\text{g}\end{array}$

(d)

Interpretation Introduction

Interpretation:

The mass of chromium present in $125\text{mol}$ is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of chromium in $125\text{mol}$ is $6498.75\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of chromium is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $125\text{mol}$

The molecular mass of chromium = $51.99\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=125\text{mol}\times \text{51}\text{.99}\text{g}/\text{mol}\\ =6498.75\text{g}\end{array}$

(e)

Interpretation Introduction

Interpretation:

The mass of iron present in $4.25\times {10}^3\text{mol}$ is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of iron in $\text{4}\text{.25}\times \text{10}{}^3\text{mol}$ is $237341.25\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of chromium is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where, n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $4.25\times {10}^3\text{or}4250\text{mol}$

The molecular mass of iron = $55.845\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=4.25\times {10}^3\text{mol}\times \text{55}\text{.845}\text{g}/\text{mol}\\ =237341.25\text{g}\end{array}$

(f)

Interpretation Introduction

Interpretation:

The mass of magnesium is to be calculated.

Concept Introduction:

The average atomic mass is numerically equal to the atomic mass which is given in the periodic table.

The formula to calculate the mass of any species for a given number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Answer to Problem 15A

The mass of magnesium $0.000105\text{mol}$ is $0.00255\text{g}$ .

Explanation of Solution

The average molecular mass is also equal to molecular mass. The mass of chromium is calculated as follows:

The formula to calculate the number of moles is,

  $n=\frac{\text{mass}}{\text{molecular}\text{mass}}$ ……….. (1)

Where,

n represents the number of moles.

Therefore the mass of the species becomes,

  $\text{mass}=n\times \text{molecular}\text{mass}$ ………… (2)

Given data:

n = $0.000105\text{mol}$

The molecular mass of magnesium = $24.305\text{g}/\text{mol}$

Plugin the values in equation (2)

  $\begin{array}{l}\text{mass}=0.000105\text{mol}\times \text{24}\text{.305}\text{g}/\text{mol}\\ =0.00255\text{g}\end{array}$