Chapter 6, Problem 8A

Interpretation Introduction

Interpretation: The number of atoms in 55.85 g of iron needs to be determined.

Concept introduction: The molar mass is defined as mass of a substance in 1 mol. The number of units of the substance in 1 mol is $6.02\times {10}^{23}$ . This is Avogadro’s number and denoted by symbol $N_A$ .

Answer to Problem 8A

  $6.02\times {10}^{23}$

Explanation of Solution

The mass of iron is given 55.85 g.

The molar mass of iron is 55.85 g/mol. Thus, 1 mol of iron atom has 55.85 g of mass. Now, 1 mol of any species has $6.02\times {10}^{23}$ atoms. Thus, 1 mol of Fe has $6.02\times {10}^{23}$ atoms of Fe.

Therefore, the number of iron atoms present in 55.85 g of iron is $6.02\times {10}^{23}$ .

Conclusion

Therefore, the number of iron atoms present in 55.85 g of iron is $6.02\times {10}^{23}$ .