First, molar mass is defined as the mass of a mole or one mole. It can also be identified with single elements, single molecules, and other substances. Molar mass is the same as molecular weight. However, the main difference is that molecular weight only describes the weight of the molecules over the elements.
Both the molar mass and molecular weight are expressed in units of grams per mole. Water is also known as H2O. It is composed of two hydrogen atoms and one oxygen atom.
An oxygen atom weighs 16 grams per mole. A hydrogen atom weighs 1 gram per mole. So multiplying 2 hydrogen atoms would yield 2 grams per mole of hydrogen plus 16 grams per mole of oxygen equals 18 grams per mole. Thus, the molecular weight or molar mass of water is 18 grams per mole. Atomic mass, on the other hand, is the mass of the atom not in motion but at rest.
Atomic mass is also the number of protons and the number of neutrons. The atomic mass of an atom is described as the sole weight of an isotope and not the average weight. Atomic mass is measured via mass spectrometry. Molar mass is computed from the atomic weight. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. I don't understand the difference between "molecular mass" and "average atomic mass".
They seem like the same thing to me. Also, what's the difference between molar mass and molecular mass? The hardest part about chemistry is keeping track of which people are using which terms, and which terms are outdated.
Is this one of these "oh, we use this term now," type of thing? Atomic mass refers to the average mass of an atom. This has dimensions of mass , so you can express this in terms of daltons, grams, kilograms, pounds if you really wanted to , or any other unit of mass. Anyway, as you said, this is an average of the masses of the isotopes, weighted by their relative abundance. It is exactly the same as the dalton, but from what I've seen, the term dalton is used more when discussing polymers, biomolecules, or mass spectra.
Molecular mass refers to the average mass of a molecule. Again, this has dimensions of mass. It's just the sum of the atomic masses of the atoms in a molecule. You don't need to calculate the relative isotopic abundance or anything for this because it's already accounted for in the atomic masses that you are using.
The term molar mass refers to the mass per mole of substance - the name kind of implies this. These are defined as the ratio of the average mass of one particle an atom or a molecule to one-twelfth of the mass of a carbon atom.
This is probably clearer with an example. Note that this is a ratio of masses and as such it is dimensionless it has no units attached to it. The relative atomic mass average atomic mass as you put it is the weighted average mass of all the isotopes of an element in a given sample, relative to the unified atomic mass unit, which is defined as one twelfth of the mass of a carbon atom in its ground state.
Sometimes called the molecular weight or relative molar mass. This is the sum total of the relative atomic masses of all the atoms in a molecule. Atomic mass is the mass of one individual unit of a substance. An important concept regarding the mole is that the atomic mass in "amu" of a substance is numerically equivalent to the mass in "g" of one mole of that substance.
To illustrate this fact, let's look at the compound sodium chloride "NaCl". The atomic mass of "NaCl" can be found by using the atomic masses of the individual elements found on a periodic table:.
This is numerically equivalent to the molar mass of "NaCl". That is to say,. So, the mass of one unit of "NaCl" is What is the difference between molar mass and atomic mass? Chemistry Matter Atomic Mass.
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