Pressure And Temperature

In summary, on the surface of Venus, the atmospheric pressure is greater than on Earth, resulting in more molecules per unit volume.
  • #1
MetalCut
21
0
Hi.

Can someone maybe give me an equation to determine the number of molecules per unit volume (N/V) when the pressure(P) and the temperature(T) is given. The pressure is in PA and the temperature is in Kelvin.

Thanx
 
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  • #2
The ideal gas law says that for an ideal gas: PV=NkT where P, V, and T are pressure (Pascals), volume(m-3), and temperature(K) respectively, N is the number of molecules, and k is Boltzmann's constant of 1.381 × 10−23 J/K
 
  • #3
I know that one. But the volume is not given, so how can i get the N/V, the number of molecules per volume?
 
  • #4
Can you solve the ideal gas law for N/V?
 
  • #5
Yeah, so I must determine the volume first before I can determine the number of molecules. Let me give you the question. Maybe you can point out what I am misssing.

On the sunlit surface of Venus, the atmospheric pressure is 9.0 x 10 6Pa, and the temperature is 740K. On the Earth's surface the atmospheric pressure is 1.0 x 10 5Pa, while the surface temp can reach 320K. These data imply that Venus has a "thicker" atmosphere at its surface than does the earth, which means that the number of molecules per unit volume (N/V) is greater on the surface of Venus than on Earth. Find the ratio (N/V)venus / (N/V)earth.

Thanx
 
  • #6
Why do you want to solve for the number of molecules?

You are trying to solve for N/V. Solve for N/V in the ideal gas law and see what it is dependent on.
 
  • #7
Ok but isn't N the number of molecules?
 
  • #8
MetalCut said:
Ok but isn't N the number of molecules?

Yes, N is the number of molecules, so as dav2008 says, solve for N/V and you will have your answer.

-Hoot:smile:
 
  • #9
Ok Thanx man.
 

1. What is the relationship between pressure and temperature?

The relationship between pressure and temperature is known as the ideal gas law. It states that as temperature increases, pressure also increases, while holding volume constant. Inversely, as temperature decreases, pressure also decreases.

2. How does pressure affect the boiling point of a substance?

As pressure increases, the boiling point of a substance also increases. This is because higher pressure increases the energy required for a liquid to overcome the external pressure and turn into a gas, resulting in a higher boiling point.

3. Can pressure and temperature be directly measured?

Yes, pressure and temperature can both be measured directly using various instruments. Pressure can be measured using a pressure gauge or manometer, while temperature can be measured using a thermometer or thermocouple.

4. Why does the pressure of a gas decrease as it expands?

The pressure of a gas decreases as it expands because the same amount of gas molecules are now spread out over a larger area. This results in fewer collisions between molecules and the container, leading to a decrease in pressure.

5. How does pressure and temperature affect the state of matter?

Increasing pressure and decreasing temperature can cause a substance to change states. For example, increasing pressure and decreasing temperature can cause a gas to condense into a liquid, or a liquid to freeze into a solid. This is because pressure and temperature affect the molecular motion and arrangement of a substance.

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