Can someone explain, in chemistry, how n=mass/molar mass?

Question

I came upon this in trying to solve for molar mass in a problem. The Ideal gas law was re-arranged to molar mass=dRT/P. or P=mass/molar mass x RT/V Where mass/V=d. I just dont understand how n=mass/molar mass.

Answer 1

PV = nRT

p = pressure, v = volume, n = moles, R = ideal gas constant, T = temp.

molecular weight = mw = grams/mole = g/mole -----> moles = g/mw... you're calling mw, molar mass fyi.

density = d = grams / volume = g/V -----> V = g/d

substitute

PV=nRT

P x (g/d) = g/mw x R x T

divide both sides by g

P/d = RT/mw

rearrange

mw = dRT/P


as to why moles = mass/molecular weight, the molecular weight = mass for 1 mole by definition. ie. moles = mass / molar mass by definition....

Answer 2

P Molar Mass

Answer 3

Molar Mass Of P

Answer 4

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RE:
Can someone explain, in chemistry, how n=mass/molar mass?
I came upon this in trying to solve for molar mass in a problem. The Ideal gas law was re-arranged to molar mass=dRT/P. or P=mass/molar mass x RT/V Where mass/V=d. I just dont understand how n=mass/molar mass.

Answer 5

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Saying the same thing in a different way... The ideal gas law (PV=nRT) is absolutely valid only for ideal gases. Real substances will cause very slight deviations in this equation, but for the most part, those deviations are too small to make any real difference. So, any liquid which can be vaporized will produce a gas phase which pretty well obeys the ideal gas law. Now, n in the equation is the number of moles of gas. For any gas, n = mass/molar mass or m/MW = n So, if you you can determine the moles of gas involved, and you know the mass of that gas, you can use the ideal gas law to calculate the molar mass of the substance: PV = (m/MW) RT rearranging gives: MW = mRT/PV

Answer 6

The molar mass is the mass per unit mole

Its units are g/mol

So if we divide mass (grams) by molar mass (grams per mole) we are left with just moles

M = m/n so n = m/M

Where M is the molar mass and m is the mass of the substance.

Answer 7

n is number of moles.

For oranges (pretending oranges all weighed the same)

n (number of oranges) x mass of each orange = total mass

For moles,

n (number of mols) x molar mass = total mass

And all credit to you for putting your finger on exactly what was holding you back.

Answer 8

molar mass = grams per mole (g/mole) by definition
moles (n) = mass / molar mass = g / g/mole = moles
if the molar mass of O2 is 32 (16 + 16), and you have an O2 mass of 8 grams, you have 8/32 moles of O2 (8 g / 32 g per mole = 0.25 moles)

Answer 9

n = the number of moles

If you take the mass of something, divided by the mass of one mole you can figure out how many moles you have.