What is the mass (in grams) of 9.83 * 1024 molecules of methanol (CH3OH) ?

523 grams First, calculate the molar mass of CH3OH Atomic weight of carbon = 12.0107 Atomic weight of hydrogen = 1.00794 Atomic weight of oxygen = 15.999 Molar mass of CH3OH = 12.0107 + 4 * 1.00794 + 15.999 = 32.04146 Now determine how many moles you have by dividing the number of atoms by avogadro's number moles = 9.83 x 10^24 / 6.0221409 x 10^23 = 16.3231 Now multiply the number of moles by the molar mass 16.3231 * 32.04146 = 523.0159557 Since we only have 3 significant figures, round the result to 3 significant figures. 523.0159557 grams = 523 grams