Molar mass and molecular weight

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Tarika Gujral 1K
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Molar mass and molecular weight

Postby Tarika Gujral 1K » Thu Oct 04, 2018 8:35 am

Technically, don’t molar mass and molecular weight refer to the same concept: the total weight (in grams) of the molecular formula?

Chem_Mod
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Re: Molar mass and molecular weight

Postby Chem_Mod » Thu Oct 04, 2018 8:55 am

Molar mass and molecular weight are similar, but they measure different quantities. Molar mass measures the mass of 6.22x1023 molecules and is expressed as g/mol. On the other hand, molecular weight measures the mass of one molecule and is expressed as amu.

Kyle Golden Dis 2G
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Re: Molar mass and molecular weight

Postby Kyle Golden Dis 2G » Thu Oct 04, 2018 11:14 am

Just to clarify, the molar mass measures the weight of 6.02 x 10^23 particles of a substance.

Julia Go 2L
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Re: Molar mass and molecular weight

Postby Julia Go 2L » Thu Oct 04, 2018 2:07 pm

The molecular weight calculates the mass of one molecule of a substance.

In comparison, the molar mass refers to the mass per mole of a substance. The molar mass can be used to calculate the number of atoms, molecules, and other units.

The two have different units.

Molar mass: grams per mole
Molecular weight: atomic mass units (amu)

One big key difference between the two is that one measures mass and the other measures weight. The distinction between mass and weight is:

mass- measure of quantity of matter
weight - measure of gravitational pull it experiences

To explain, the molecular weight of something would change on a different planet compared to Earth. (since the force of gravity changes.) Mass would stay constant no matter what environment.


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