# Calculating Particle Density in an Ideal Gas at STP

• blazeuofa
In summary: Avogadro's #) divided by the volume occupied by one mole of gas (22.4L at STP).In summary, to determine the number density of particles in a gas at STP, we use the equation pV=nRT to calculate the number of molecules in one mole of gas (Avogadro's #) divided by the volume occupied by one mole of gas (22.4L at STP). This results in an answer of 2.68x10^25 particles per unit volume.

## Homework Statement

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

pV=nRT

blazeuofa said:

## Homework Statement

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

## The Attempt at a Solution

pV=nRT

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

## What is a "Simple Ideal Gas"?

A simple ideal gas is a theoretical model of a gas that is composed of particles that have negligible volume and do not interact with each other. This model is often used in scientific calculations and experiments as it simplifies the behavior of gases.

## What are the assumptions made in a Simple Ideal Gas problem?

The assumptions made in a Simple Ideal Gas problem include: 1) particles have negligible volume, 2) particles do not interact with each other, 3) particles move in random straight-line motion, and 4) the average kinetic energy of the particles is directly proportional to temperature.

## How do you calculate the pressure of a Simple Ideal Gas?

The pressure of a Simple Ideal Gas can be calculated using the ideal gas law, which states that pressure (P) is equal to the number of moles (n) of gas multiplied by the gas constant (R) and the temperature (T) in Kelvin, divided by the volume (V) of the gas. This can be expressed as the equation: P = (nRT)/V.

## What is the relationship between temperature and pressure in a Simple Ideal Gas?

According to the ideal gas law, as temperature increases, the pressure of a Simple Ideal Gas will also increase if the volume and number of moles remain constant. This is because an increase in temperature means an increase in the average kinetic energy of the particles, causing them to collide with the walls of their container with greater force, thus increasing the pressure.

## How does a Simple Ideal Gas problem differ from a real gas problem?

A Simple Ideal Gas problem assumes that the gas particles have no volume and do not interact with each other, while real gases exhibit some volume and do interact with each other. This can cause deviations from the ideal behavior predicted by the ideal gas law, especially at high pressures and low temperatures. Real gases also have specific gas constants, whereas the ideal gas law uses a universal gas constant that applies to all ideal gases.