# An average cup of coffee contains about 125 mg of caffeine, C_8H_10N_4O_2. How many moles of caffeine are in a cup, and how many molecules of caffeine?

Nov 22, 2015

The molecular mass of caffeine is $194.19$ $g \cdot m o {l}^{-} 1$.
Moles of caffeine in a cup $=$ (125xx10^-3g)/(194.19*g*mol^-1 $=$ ?? $m o l$.
The above calculation gives an answer in moles. This is simply a number, i.e. N_A*mol*xx(125xx10^-3g)/(194.19*g*mol^-1 $=$ ??