Question

Calculate the number of moles and molecules present in 0.032 mg of methane (C=12,H=1)

Answer 1

Hope the solution helps.

Answer 2

HEYA,

Here is your answer


To get the moles of methane, we first get its molar mass by adding the masses of C and H. There are C atoms and 4 H atom:
CH4 = 12 + 4*1 = 16 g/mol
Then we divide the given mass by the molar mass:
0.032 mg = 0.000032 g
0.000032 g / (16 g/mol)
= 0.000002 mol or 2 x 10^(-6) mol

To get the molecules present, recall that 1 mole of a substance is equal to 6.022 x 10^23 particles / mol (Avogadro's number). We'll multiply this to the the moles:
6.022 x 10^23 / mol * 2 x 10^(-6) mol
= 1.2044 x 10^18 molecules of CH4