How many molecules are in 12 grams of methane (CH 4) ?

To calculate number of molecules, we first need to calculate the number of moles of methane.

Number of moles of methane = / frac{Given mass}{Molar mass of methane}

Molar mass of methane = 16.04 g/mol

Given mass of methane = 12 g

Number of moles of methane=/frac{Given mass}{Molar mass of methane}

=/frac{12}{16.04}

= 0.74 mol

Number of molecules of methane = 0.74/times 6.023 / times 10^{23}

= 4.5 * e²³

12 grams of methane is one mole. So there are N (Avogadro) = 6.22 x 10^23 molecules in one mole of methane