lbmol to kmol

[droopy]

How do I convert lbmol to kmol ???

[Knight]

How do I convert lbmol to kmol ???

Ah... Working with the Ideal Gas Law, Are we?

A mol (sometimes gmol, g-mol, or mole, not to be confused with the rodent) denotes an amount of matter. Specifically one mol is 6.0251 x 10^23 molecules of a substance, a standard number of molecules known as Avogadro’s number. Strictly speaking, mol does not have dimensions of mass; rather, mol is a primary dimension in and of itself, i.e. the amount of matter. The number of mols of a substance is denoted by the letter n. Molecular weight (M) is defined as the number of grams (g) per mol of a substance. M is obtained from standard periodic charts of the elements. For example, the molecular weight of nitrogen is M(nitrogen) = 14.0067 g/mol. Nitrogen in its gaseous or vapor state occurs as a diatomic molecule, N2; thus, M(gaseous nitrogen) = 28.0134 g/mol. Since air is made up predominantly of nitrogen gas, the molecular weight of air is very close to that of nitrogen, i.e. M(air) = 28.97 g/mol.

In S.I. units, the kilogram (kg) is preferred over the gram; thus the kilogram-mol (kmol, sometimes kg-mol or kg-mole) is often used instead of the mol. By definition, a kmol is defined as 1000 mol, or 6.0251 x 10^26 molecules of the substance. The molecular weight of air in terms of kg and kmol is then:

Code: Select all

         28.97 g   1000 mol     kg            kg
M(air) = ------- x -------- x ------ = 28.97 ----
           mol       kmol     1000 g         kmol

In English units, the pound-mass (lbm) is the standard unit of mass. In order to use the same molecular weights as those listed on the periodic chart, the pound-mol, (lbmol, sometimes lb-mol, lbm-mol, or lbm-mole) is defined. The molecular weight of elemental nitrogen, for example, in English units is M(nitrogen) = 14.0067 lbm/lbmol, and the molecular weight of air is:

M(air) = 28.97 lbm/lbmol.

[gotIt]

Ah, thank you; I was confused on that too.

One note, though: there's one typo in there that threw me for a second until I realized it was actually a typo; you have "29.97 kg/kmol" instead of "28.97".

[Knight]

Ah, thank you; I was confused on that too.

One note, though: there's one typo in there that threw me for a second until I realized it was actually a typo; you have "29.97 kg/kmol" instead of "28.97".

Good catch. I've corrected the original