Calculating Particle Density in an Ideal Gas at STP

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Homework Help Overview

The discussion revolves around calculating the number density of particles in an ideal gas at standard temperature and pressure (STP), specifically at T=273 K and P=1 atm. Participants are exploring the concept of number density and its relation to gas laws.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are attempting to understand the definition of "number density of particles" and how it relates to the ideal gas law (pV=nRT). Questions are raised about the relationship between the number of molecules in a mole and the volume occupied by a mole of gas at STP.

Discussion Status

Some participants have provided clarifications regarding the meaning of number density and its dependence on the number of gas molecules per unit volume. There is an ongoing exploration of how to apply Avogadro's number and the volume of gas at STP to find the solution.

Contextual Notes

Participants are noting the importance of unit consistency when applying the ideal gas law and are questioning how to effectively piece together the information regarding volume and the number of molecules.

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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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