Calculating Particle Density in an Ideal Gas at STP

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The discussion focuses on calculating the number density of particles in an ideal gas at standard temperature and pressure (STP), which is determined to be 2.68x10^25 particles per cubic meter. Number density refers to the number of gas molecules per unit volume, contrasting with mass density, which measures mass per unit volume. Participants clarify that at STP, one mole of gas occupies 22.4 liters, and Avogadro's number indicates the number of molecules in a mole. The equation pV=nRT is emphasized, with attention to ensuring correct unit conversions. Understanding these concepts is essential for accurately calculating particle density in gases.
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Homework Statement



Determine the number density of particles in a gas at STP (T=273, p=1atm)

Homework Equations



Answer is 2.68x1025

The Attempt at a Solution



pV=nRT


I don't really understand what the "number density of particles" means please help!
 
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blazeuofa said:

Homework Statement



Determine the number density of particles in a gas at STP (T=273, p=1atm)

Homework Equations



Answer is 2.68x1025

The Attempt at a Solution



pV=nRT


I don't really understand what the "number density of particles" means please help!

It means the number of gas molecules per unit volume. Mass density is mass per unit volume. For a gas, the pressure and volume depends on the number of molecules, not their mass.

How many molecules of gas are then in a mole of the gas? How much volume does a mole of gas occupy at STP?

AM
 
hmm I can't quite get the right answer. V=22.4L and avagadros # is the molecules in one mole. How do I piece this together?
 
blazeuofa said:
hmm I can't quite get the right answer. V=22.4L and avagadros # is the molecules in one mole. How do I piece this together?

Be careful of units here... when using PV=nRT what is the units of volume?

So you know Avogadro's # is the number of molecules in one mole... so put the pieces together. As Andrew said, the number density the number of gas molecules per unit volume
 

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