Q. 7.94 - An Introduction to General, Organic, and Biological Chemistry

Question

How many grams are in $2.25$ mole of each of the following? ($7.3$)

a. ${\mathrm{N}}_2$

b. $\mathrm{NaBr}$

c. ${\mathrm{C}}_6{\mathrm{H}}_{14}$

Step-by-Step Solution

Answer

(a) The mass of ${\mathrm{N}}_2$ in $2.25$ mole is $63$ g

(b) The mass of $\mathrm{NaBr}$ in $2.25$ mole is $231.75$ g

(c) The mass of ${\mathrm{C}}_6{\mathrm{H}}_{14}$ in $2.25$ mole is $193.5$ g

Part (a) Step 1: Given information

We need to find the mass of given compound i.e. ${\mathrm{N}}_2$ 

Part (a) Step 2: Explanation

We know that

The molar mass of ${\mathrm{N}}_2$ is $28 \mathrm{g}/\mathrm{mole}$

And a mole of the element is equal to molar mass

Therefore,

$$\begin{gathered} 1 \mathrm{mole}=28 \mathrm{g} \\ 2.25 \mathrm{mole}=\frac{28 \mathrm{g} \times 2.25\cancel{ \mathrm{mol}}}{\cancel{\mathrm{mol}}}=63 \mathrm{g} \end{gathered}$$

Part (b) Step 1: Given information

We need to find the mass of given compound i.e. $\mathrm{NaBr}$

Part (b) Step 2: Explanation

We know that

The molar mass of $\mathrm{NaBr}$ is $103 \mathrm{g}/\mathrm{mole}$

And a mole of the element is equal to molar mass

Therefore,

$$\begin{gathered} 1 \mathrm{mole}=103 \mathrm{g} \\ 2.25 \mathrm{mole}=\frac{103 \mathrm{g}\times 2.25 \cancel{\mathrm{mol}}}{\cancel{\mathrm{mol}}}=231.75 \mathrm{g} \end{gathered}$$

Part (c) Step 1: Given information

We need to find the mass of given compound i.e. ${\mathrm{C}}_6{\mathrm{H}}_{14}$ 

Part (c) Step 2: Explanation

We know that

The molar mass of ${\mathrm{C}}_6{\mathrm{H}}_{14}$ is $86 \mathrm{g}/\mathrm{mole}$

And a mole of the element is equal to molar mass

Therefore,

$$\begin{gathered} 1 \mathrm{mole}=86 \mathrm{g} \\ 2.25 \mathrm{mole}=\frac{86 \mathrm{g}\times 2.25 \cancel{\mathrm{mol}}}{\cancel{\mathrm{mol}}}=193.5 \mathrm{g} \end{gathered}$$