Molar Mass and Molecular Mass Difference?

[Sandra Kim 2B]

Was just wondering what's different between molar mass and molecular mass since the process for finding both seem to be practically identical (correct me if I'm wrong please I forgot everything about chem since hs). Or is this just not something I should worry about?

[Mansi Solanki 3A]

The molar mass is defined as the mass of a certain number of atoms, molecules, or compounds within one mole of the compound. It is measured in g/mol. The molecular mass is defined as the mass of one molecule. It is measured in amu.

Usually when you are calculating them for something like water, both the molar mass and molecular mass is the same (18.02 g/mol or 18.02 amu). For the most part, we use the molar mass in problems because they can then be used to convert to moles and relate different compounds and elements.

[Day Preciado 1H]

So are molecular mass and molar mass basically interchangeable?

[Uyenvy Nguyen 1D]

I think that they are the same numerically, but the units for molar mass is grams, while molecular mass is amu. They are a bit similar, so I can see how this can be confusing to think about.

[Ansh Patel 2I]

I believe that molar mass is the mass of one mole of a certain compound (C=12.01 g/mol), while molecular mass is the mass of a single molecule of a substance measured in amu (One molecule of H2O=18.02 amu).

[Nico Medina]

I believe that they are the same thing, as, by definiton, 1 amu = 1 g/mol. They will be the same for each respective element or compound, but as mentioned before, molar mass (g/mol) is useful for unit conversions. Hope this helps!

[Lilly Catarozoli 1B]

I believe they can be used interchangeably. It depends on what units you are trying to get for your answer.

[Heidi Buri 2I]

Usually, the molecular mass is thought of as the mass of particular molecules. There can be various molecular masses based on the different masses of isotopes. For example, the isotopes of carbon (carbon-12, carbon-13, and carbon-14) would all have different molecular masses due to their different isotopes. The molecular mass can also be the mass of any number of molecules. Different from the molecular mass, the molar mass is in terms of avagadro's number (6.022x10^23). Additionally , they differ in the units used. The units for molecular mass are atomic mass units while the units for molar mass are grams/moles.

[DPatel_2L]

They basically mean the same thing but have different units.

[IanWheeler3F]

Adding on to the isotope comment, the reason carbon's amu is 12.011 and not 12 is because the 12.011amu is the average of the masses of all carbon isotopes, so while most carbon is 12amu, there is a smaller fraction of carbon in the universe that weights more (13amu and 14amu) so after dividing the total mass of all the carbon atoms (all different masses depending on isotope) by the total carbon atoms present, you get a number slightly above 12

[joshtully]

What is an amu? I understand that it is a unit for molecular mass, but what does it stand for?

[Bai Rong Lin 2K]

when do the units matter or when do you know which unit do you use?

[aashmi_agrawal_3d]

They are basically the same but molar mass is measured in grams while molecular mass is measured in amu.

[Moura Girgis 1F]

How would you know which units to use per molar mass and which to use for molecular mass? Is it grams and moles for molar mass but formula units for molecular mass?

[jessicaosuna_1F]

Molar mass is specific to an atom. Molecular mass is the mass of the whole molecule, so that would be the molar masses of each individual atom within the molecule added up.

[angelasavage]

How would you know which units to use per molar mass and which to use for molecular mass? Is it grams and moles for molar mass but formula units for molecular mass?

The molar mass of an element (grams for 1 mol of the atoms of an element) is given via the periodic table. The molecular mass is in amu, and is the total mass of a molecule (multiplying the molar masses of each element by the numbers indicated in the molecular formula and then adding them up).

[Kaiya_PT_1H]

What is an amu? I understand that it is a unit for molecular mass, but what does it stand for?

amu means "atomic mass unit" which is a measurement based on the carbon atom: 1 amu = 1/12 the mass of an unbound carbon atom. https://www.thoughtco.com/definition-of ... amu-604366

[Juliana Rosales 1H]

They are the same thing but with different units. The units matter because then the answer will be wrong.

[Ava_Basileo_2J]

The difference is in the units. Simple:

1. molar mass is in grams per mol
2. molecular mass is in amu (atomic mass units)

[Moura Girgis 1F]

Those two are pretty interchangeable, they just require different units I think.

[Carly_Lipschitz_3H]

Molar mass is in the units grams/mole or kilograms/mole. Molecular mass uses atomic mass units (amus).

[205323697]

When would we prefer to use one of them instead of the other?

[Audrey Banzali-Marks 1A]

Molar mass is the amount of one mole of any substance, I believe. Usually it might refer to the mass of a mole of atoms of a certain element. Molecular mass, on the other hand, refers to the mass of one mole of molecules. Although one molecule may be made up of several different atoms, the mass would be determined with 1 mole of complete molecules. I hope that helps!

[Elizabeth Kim 2K]

Molar mass and molecular mass have the same magnitude but different units. While molar mass is measured in grams per mole (g/mol), molecular mass is measured in atomic mass units (amu). For example, the molar mass of sodium is 22.99 g/mol, but the molecular mass of sodium is 22.99 amu. Although the units are different, the numeric measure, 22.99, is the same in both cases.

[Kaitlyn Bateman 1L]

When is it appropriate to use amu versus just grams?