Change in pressure using PV=nRT

In summary, the conversation discusses the change in pressure of a gas confined in a tank when the temperature is raised and half of the gas is withdrawn. The ideal gas law (PV=nRT) is used to calculate the initial and final temperatures and the new pressure in the tank. However, it is revealed that the volume is not halved, but the number of particles is, which results in a different calculation for the final pressure.
  • #1
rinarez7
27
0
1b]1. Gas is confined in a tank at a pressure of
6.5 atm and a temperature of 9.4◦C.
If half of the gas is withdrawn and the
temperature is raised to 62.4◦C, what is the
new pressure in the tank? Answer in units of
atm.



2. PV=nRT
Ti= 9.4 C + 273= 282.4K
Tf= 62.4 C +273= 335.4K




3. PV= nRT, n and R are constants, therefore I used PV= T
So, initially, 6.5atmVi= 282.4K giving, Vi = 43.446

I then used (1/2) 43.446 as Vf and solved for Pf
Pf= Tf/ Vf=> 15.439 atm

But this isn't right, I know. What am I missing?? .
 
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  • #2
My thought would be that "half of the gas is withdrawn" means that the number of particles n is halved, and the volume is kept constant, not the other way around.
 
  • #3
It doesn't mention the volume has been reduced by a half, the amount of gas has been reduced by a half so you need to use 0.5n.
 
  • #4
Thanks to the both of you!
 

1. What is the ideal gas law and how does it relate to pressure changes?

The ideal gas law, PV=nRT, is an equation that describes the relationship between the pressure, volume, temperature, and number of moles of an ideal gas. It states that as the temperature and volume of a gas increase, the pressure will also increase, while the number of moles remains constant.

2. How does changing the volume of a gas affect its pressure?

According to the ideal gas law, as the volume of a gas increases, the pressure will decrease, and vice versa. This is because an increase in volume results in the gas molecules having more space to move around, therefore exerting less force on the container walls and decreasing the pressure.

3. What is the relationship between temperature and pressure in the ideal gas law?

The ideal gas law states that as the temperature of a gas increases, the pressure will also increase, while the volume and number of moles remain constant. This is because an increase in temperature causes the gas molecules to have more kinetic energy, resulting in more collisions with the container walls and an increase in pressure.

4. How does changing the number of moles of a gas affect its pressure?

In the ideal gas law, the number of moles is directly proportional to pressure. This means that as the number of moles of a gas increases, the pressure will also increase, while the volume and temperature remain constant. This is because there are more gas molecules present to collide with the container walls, resulting in a higher pressure.

5. What factors can cause a change in pressure for a gas?

According to the ideal gas law, changes in pressure can occur due to changes in temperature, volume, or the number of moles of a gas. Other factors that can also affect pressure include changes in the container size or shape, the presence of other gases or particles in the container, and intermolecular forces between gas molecules.

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