What is the Number Density of Gas Molecules at Sea Level?

In summary, to estimate the number density of gas molecules in the Earth's atmosphere at sea level, the ideal gas law can be used with the assumption of standard temperature (273 K). Using this, the number density is calculated to be approximately 2.7 * 10^25 molecules/m^3.
  • #1
bcjochim07
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0

Homework Statement


Estimate the number density of gas molecules in the Earth's atmosphere at sea level.

Homework Equations





The Attempt at a Solution



The question doesn't give me any further information and I am wondering about temperature---should I just say it's at STP? I found in my book that the density of air at STP is 1.3 kg/m^3.

Here's what I did:
PV=NkT

P/kT =N/V
(101300Pa)/(1.38E-23)(273 K)=2.7 * 10^25 molecules/m^3
 
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  • #2
If they do not specify a temperature, assume standard temperature.

Looks good to me.
 
  • #3
As a check / alternative - work out how much an 'air' molecule weighs and use the density to work how many molecules.
 

Related to What is the Number Density of Gas Molecules at Sea Level?

1. What is number density of air?

Number density of air refers to the number of air molecules per unit volume. It is typically measured in units of particles per cubic meter (particles/m3).

2. How is number density of air related to air pressure?

The number density of air is directly proportional to air pressure, meaning that as air pressure increases, the number density of air also increases. This is because an increase in air pressure results in more air molecules being present in a given volume.

3. What factors affect the number density of air?

The number density of air is affected by temperature, air pressure, and humidity. As temperature and air pressure increase, the number density of air also increases. However, as humidity increases, the number density of air decreases.

4. How is number density of air measured?

Number density of air is typically measured using instruments such as a gas analyzer or a mass spectrometer. These instruments can accurately measure the number of air molecules present in a given volume of air.

5. Why is number density of air important?

The number density of air is an important concept in atmospheric science and meteorology. It helps us understand the composition and behavior of the Earth's atmosphere, and is essential for studying air pollution and weather patterns. It is also important in industries such as aviation and aerospace, where knowledge of air density is crucial for safe flight operations.

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