Problem with ideal gas pressure

In summary, two bulbs, A and B, are connected to a three way tap T, with bulb A filled with an ideal gas at 10oC and bulb B filled with an ideal gas at 100oC. The two bulbs are connected with A maintained at 10oC and B at 100oC. The pressure at equilibrium can be calculated using the equation PV=nRT, with the total volume and total number of moles known. The final temperature of the system can also be found by setting up three equations and solving for the three unknowns.
  • #1
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Homework Statement



Diagram here:
http://img99.imageshack.us/img99/7189/systemgk9.jpg

Two bulbs, A of volume 100cm3 and B of volume 50cm3 , are connected to a three way tap T which enables them to be filled with gas or evacuated. The volume of the tubes may be neglected.
Initially bulb A is filled with an ideal gas at 10oC to a pressure of 3.0 x 105 Pa. Bulb B is filled with an ideal gas at 100oC to a pressure of 1.0 x 105 Pa. The two bulbs are connected with A maintained at 10oC and B at 100oC. Calculate the pressure at equilibrium.

Homework Equations


PV = nRT

The Attempt at a Solution



I have the total Volume, total n but I can't find the final temperature of the system.

I'm learning A-level Physics and this problem comes from a book, the Advanced Level Physics by Michael Nelkon. Please help me. Thank you in advance.
 
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  • #2
Initially you have [itex]P_A V_A=n_A R T_A[/itex] and [itex]P_B V_B=n_B R T_B[/itex]. You can figure out all of those numbers, right? Finally you have a new pressure [itex]P[/itex] and new molar numbers [itex]n'_A[/itex] and [itex]n'_B[/itex], three unknowns. So you need three equations to find them. You have two PV=nRT equations in the final state (one for each bulb) and [itex]n_A+n_B=n'_A+n'_B[/itex].
 
  • #3


The problem with ideal gas pressure in this scenario is that the ideal gas law (PV = nRT) assumes that the gas particles are point masses with no volume and that there are no intermolecular forces between them. However, in reality, gas particles do have volume and there are intermolecular forces present, especially at high pressures and low temperatures. This can lead to deviations from the ideal gas law and can affect the accuracy of the calculated pressure at equilibrium.

To solve this problem, you can use the combined gas law, which takes into account the volume and temperature changes of the gases as they are mixed. The equation is P1V1/T1 = P2V2/T2, where P1 and T1 are the initial pressure and temperature of one gas, P2 and T2 are the final pressure and temperature of the mixture, and V1 and V2 are the initial and final volumes of the gas.

Using this equation, you can calculate the final temperature of the system by setting up two equations: one for the initial state (bulb A) and one for the final state (mixture of gases). Then, you can solve for the final pressure using the ideal gas law, using the final temperature that you calculated.

It's important to note that this solution is an approximation and may not be completely accurate due to the limitations of the ideal gas law. However, it should give you a reasonable estimate of the pressure at equilibrium.
 

FAQ: Problem with ideal gas pressure

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

The ideal gas law is a mathematical equation that describes the relationship between the pressure, volume, temperature, and number of moles of an ideal gas. It states that for a given amount of gas at a constant temperature, the pressure and volume are inversely proportional. This means that as pressure increases, volume decreases, and vice versa.

What factors can cause a problem with ideal gas pressure?

There are several factors that can cause a problem with ideal gas pressure. These include deviations from ideal gas behavior, such as intermolecular interactions or non-uniform temperature or pressure. Additionally, impurities in the gas or incorrect measurements can also affect ideal gas pressure.

How do you solve a problem with ideal gas pressure?

To solve a problem with ideal gas pressure, you can use the ideal gas law equation, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. You will need to rearrange the equation to solve for the desired variable and ensure that all units are consistent. If there are impurities or deviations from ideal gas behavior, additional equations or corrections may need to be applied.

What are the limitations of the ideal gas law?

The ideal gas law is a simplified model of gas behavior and has some limitations. It assumes that gas particles have no volume and no intermolecular interactions, and that temperature and pressure are uniform throughout the gas. These assumptions may not hold true in real-world situations, leading to deviations from ideal gas behavior and inaccurate calculations.

How is ideal gas pressure measured in a laboratory setting?

Ideal gas pressure can be measured in a laboratory using instruments such as a manometer or a barometer, which measure the height of a column of liquid in a tube to determine pressure. The pressure can also be measured using a pressure sensor connected to a computer, which can record and analyze the data. It is important to ensure that the gas being measured is pure and that the measurements are taken at a uniform temperature and pressure to obtain accurate results.

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