Question

How many moles of water molecules, h2o, are present in a 27 gram sample of water?

Answer 1

Answer:

1.5 moles

Explanation:

The formula to calculate number of moles (n) is

n = m/m.m          where

m = mass (in gram)

m.m = molar mass (g/mol)

Mass of the water molecules has been given in the question to be 27 g

Atomic mass of hydrogen (H) = 1 g/mol

Atomic mass of oxygen (O) = 16 g/mol

Molar mass of water (H₂O) = (2 ₓ 1) + 16 = 18 g/mol

n = 27/18

n = 1.5 moles

1.5 moles of water molecules (H₂O) are present in 27 gram sample of water.

Answer 2

Molar mass of H2O = 1 x 2 (of 2 H) + 16 (of 1 O)
No. of moles of water = Mass/Molar mass = 27g/(18 g/mol) = 1.5 mol