Simple Ideal Gas problem

  • Thread starter blazeuofa
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  • #1
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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!
 

Answers and Replies

  • #2
Andrew Mason
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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!
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
 
  • #3
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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?
 
  • #4
142
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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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