Question

Can someone please explain this to me! How many atoms of oxygen are in 5.00 g of ethanol, C2H6O?

A. 6.52 × 1022                           B. 9                                          C. 5.52 × 1024               D. 6.02 × 1023

Answer 1

Molar mass of ethanol (C₂H₅OH) = 46 gm / mole, i.e.- one mole of ethanol weigh 46 gm.

moles of ethanol available = mass / molar mass = 5 gm / 46 gm / mole = 0.108 mole

one mole of  ethanol (C₂H₅OH) contains one mole of oxygen atom, thus, 0.108 mole of  ethanol (C₂H₅OH) contains 0.108 mole of oxygen atom

one mole atom = 6.023 x 10²³ number of atoms

or, 0.108 mole of oxygen = (0.108) x 6.023 x 10²³ number of atoms = 6.51 x 10²² number of atoms

Ans - "A"