Question

How many molecules of CH4 are in 24.1 g of this compound?

Answer 1

1) find molar mass of CH₄

$=12.01+4(1.01)\\\\=16.05\ g/mol$

2) determine moles of CH₄

$=24.1g\ CH_{4}\ x\ \frac{1\ mol\ CH_{4}}{16.05g\ CH_{4}}\\\\=1.501557632\ mol\ CH_{4}$

3) multiply by avogadro's number

$=1.501557632\ mol\ CH_{4}\ x\ \frac{6.022\ x\ 10^{23}\ molecules\ CH_{4}}{1\ mol\ CH_{4}} \\\\=9.04238006\ x\ 10^{23}\\\\=9.04\ x\ 10^{23}\ molecules\ CH_{4}$