# What is the number of molecules of 140 g of CO?

Nov 30, 2016

$3.01 \times {10}^{24}$

#### Explanation:

The molar mass of carbon monoxide ($C O$) is 28.01 g/mol.

First calculate the number of moles of CO:
$\frac{140 g}{28.01 \frac{g}{m o l}} = 5.00 m o l$

Then multiply by Avogadro's number to obtain the number of molecules:
$5.00 m o l \times 6.022 \times {10}^{23} m o {l}^{-} 1 = 3.01 \times {10}^{24}$