Q22P - Chemistry: Molecular Nature Of Matter And Change

Question

Oxygen is required for the metabolic combustion of foods. Calculate the number of atoms in 38.0 g of oxygen gas, the amount absorbed from the lungs at rest in about 15 min.

Step-by-Step Solution

Answer

The number of atoms is $\mathbf{1}\mathbf{.}\mathbf{43}\mathbf{\times }{\mathbf{10}}^{\mathbf{24}}\mathbf{O}\mathbf{ }\mathbf{atoms}$

Step 1: Definition of number of atoms

The number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus is defined as number of atoms.

Step 2: Calculations of number of atoms in 38.0 g of oxygen gas

Number of atoms is calculated as: 

$\mathbf{=}\mathbf{38}\mathbf{.}\mathbf{0}\mathbf{ }\mathbf{g}\mathbf{ }{\mathbf{O}}_{\mathbf{2}}\left(\frac{\mathrm{mol} O_2}{32.00 g O_2 }\right)\left(\frac{2\mathrm{molO} \mathrm{atoms}}{1\mathrm{mol} O_2}\right)\left(\frac{6.022\times {10}^{23 }\mathrm{atoms}}{{\mathrm{molO}}_2}\right)$

Therefore, the number of atoms $\mathbf{=}\mathbf{1}\mathbf{.}\mathbf{43}\mathbf{\times }{\mathbf{10}}^{\mathbf{24}}\mathbf{ }\mathbf{O}\mathbf{ }\mathbf{atoms}$