Question

Approximately how much greater in mass is a d2o molecule than an h2o molecule? (assume the oxygen atoms have a mass number of 16. deuterium, d, is an isotope of hydrogen with a mass number of 2, 2h.)

Answer 1

`D_2O` molecule is greater than
`H_2O` molecule by 2 amu.

Step-by-step explanation:

Mass of
`H_2O` molecule:

`M_(H_2O)`= 2 × 1 amu + 1 × 16 amu = 18 amu

Mass of
`D_2O` molecule:

`M_(D_2O)`= 2 × 2 amu + 1 × 16 amu = 20 amu

Difference between mass of
`D_2O \& H_2O`

`M_(D_2O)-M_(H_2O) =20 amu - 18 amu = 2 amu`

`M_(D_2O) =2+M_(H_2O)`

`D_2O` molecule is greater than
`H_2O` molecule by 2 amu.

Answer 2

The deuteriuoted water that is
`D_(2)O` consists of an isotope of hydrogen in place of hydrogen from the normal water. The approximate mass of deuteriuoted water and normal water can be calculated as {(2×2)+16} = 20. However the exact mass of
`D_(2)O` is 20.027 g/mole, whereas the mass of water can also be calculated as- {(1×2)+16}=18, however the exact mass of (
`H_(2)O`) molecule is 18.015 g/mole. Thus the difference between the mass of the molecules are (20.027 - 18.015) = 2.01 2g/mole.