Chapter 10.1, Problem 12SSC

Interpretation Introduction

Interpretation: The mass of 0.25 mol of carbon- $12$ atom needs to be calculated.

Concept Introduction: In 1 mol of any substance, there are $6.022\times {10}^{23}$ units of that substance. These units can be atoms and molecules. The number of units in 1 mol of any substance is known as Avogadro’s number. It is denoted by the symbol N_A.

Answer to Problem 12SSC

The mass of 0.25 mol of C-12 atom is $1.8\times {10}^{24}\text{ amu}$ .

Explanation of Solution

Given Information: The number of moles of C-12 atom is 0.25 mol.

Calculation: In the given moles of C-12, the number of C-12 atoms can be calculated as follows:

  $N=n\times {\text{N}}_{\text{A}}$

Putting the values,

  $\begin{array}{l}N=\left(0.25\text{ mol}\right)\left(6.022\times {10}^{23}\text{ atoms/mol}\right)\\ =1.5\times {10}^{23}\text{ atoms}\end{array}$

Now, the mass of 1 C-12 atom is 12 amu thus, the mass of $1.5\times {10}^{23}$ C-12 atoms can be calculated as follows:

  $\begin{array}{l}m=\left(1.5\times {10}^{23}\right)\left(12\text{ amu}\right)\\ =1.8\times {10}^{24}\text{ amu}\end{array}$

Conclusion

Thus, the mass of 0.25 mol of C-12 atom is $1.8\times {10}^{24}\text{ amu}$ .