What is the mass (in grams) of 9.49 * 1024 molecules of methanol (CH3OH) ?

1 mol of any substance contains 6.022 x 10^23 units. These units could be atoms that make up an element or molecules that make up a compound.

1 mol of methanol contains 6.022 x10^23 molecules of methanol.

Mass of one mole of methanol is 32.04 g

6.022x10^23 molecules of methanol weighs 32.04 g

Therefore 9.49x10^24 molecules of methanol weigh - 32.04 / (6.022x10^23) x (9.49 x10^24) = 504.9 g