Question

Calculate the no. of molecules present in 0.5 moles of CO2?

Answer 1

Number of molecules
= no. of moles × N•
= 0.5 × 6.022×10^23
= 3.011 × 10^23 molecules


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Answer 2

The Number of molecules in 1 mole of Carbon Dioxide $\left(\mathrm{CO}_{2}\right)$ is equal to Avogadro’s number which is equal to $6.02 \times 10^{23}$.  

Therefore the Number of molecules in 0.5 moles of Carbon Dioxide $\left(\mathrm{CO}_{2}\right)$ is  

= half of Avogadro’s number  

$=\frac{\left(6.02 \times 10^{23}\right)}{2}=3.01 \times 10^{23}$.  

The mass of 1 mole of $\mathrm{CO}_{2}$ or 1 molecule of $\mathrm{CO}_{2}$ is 44 units. Therefore mass of half a mole is 22 units.

This means 22 units of mass of $\mathrm{CO}_{2}$ contains $\bold{3.01 \times 10^{23}}$.