Question

Suppose the chemists had chosen ${10}^{20}$ as the number of particles in a mole. What would be the molar mass of oxygen gas?

• A. $5.32\times {10}^{-3}\text{g/mol}$
• B. $6.22\times {10}^{23}\text{g/mol}$
• C. $6.32\times {10}^{-4}\text{g/mol}$
• D. $8.32\times {10}^{-3}\text{g/mol}$

Answer 1

The correct option is A $5.32\times {10}^{-3}\text{g/mol}$

According to the present concept of mole,
$6.022\times {10}^{23}$ molecules of oxygen weight = $32\text{g}$
Therefore,
Mass of 1 molecule of oxygen = $\frac{32}{6.022\times {10}^{23}}=5.32\times {10}^{-23}\text{g}$
If the mole contained ${10}^{20}$ particles
The mass of one mole i.e., ${10}^{20}$ particles
$=5.32\times {10}^{-23}\times {10}^{20}=5.32\times {10}^{-3}\text{g}$
Therefore,
Molar mass of oxygen = $5.32\times {10}^{-3}\text{g}$