Question

Calculate molar mass of ethanol and number of hydrogen atoms present in 2.3 g of it 

Answer 1

Ethanol (C₂H₅OH)

Molecular weight calculation:

12.0107 + 1.00794*3 + 12.0107 + 1.00794*2 + 15.9994 + 1.00794

= 46.06844 g/mol

Calculation hydrogen atoms in 2.3g of ethanol

Thus 2.3 g / 46 g / mol = 0.05 moles 

0.05 moles * 6.02 x 10E23 molecules per mole (Avogadro number) = 30100000000000000000000 molecules of C₂H₅OH 

Thus, as you have 6 atoms of hydrogen per molecule, you have then 6 * 30100000000000000000000 = 

180600000000000000000000 atoms of hydrogen