Thanks for your help ya'll!!!
More on gases... A few questions:
1) A sample of helium is in a container with a movable piston. If the temperature is increased from 5*C to 10*C while keeping pressure constant, the volume of the gas will then be?
PV=nRT (Ideal Gases)
...so it goes from 278K --> 283K.
The answers says: greater than one-half, but less than twice the original volume.
Can anyone care to explain how this is greater than one half, but less than twice the volume. I might need to see it from someone's perspective.
V1/T1 = V2/T2
V2 = V1(T2/T1) = V1(283/278) = 1.02V1 (greater than 0.5x but less than 2x)
2)A mixture of two moles of oxygen gas, 5 moles of neon, 3 moles of hydrogen gas, 2moles of nitrogen gas, and 5 moles of helium gas is in a rigid container. If the container has a pinhole, then the concentration of which gas will increase most with time?
Ans: Oxygen
I know the effusion rate will be the slowest for the heavier gas in the mixture, but isn't Neon heavier than Oxygen? Thus, it should be the most in the container over time... right?
Oxygen gas exists as O2 (16x2 = 32 g/mole), while Ne being an inert gas exists as Ne (20x1 = 20). So oxygen gas is heavier-->Moves slower-->Efusion rate lower-->Higher concentration over time.
3)At low temperature and high pressures, the measured pressure of a gas is:
The ideal gas law works under high temp and low pressure. Under low temp and high pressure, the gas molecules come close to one another and the Van der Waal forces become significant. In other words, gas molecules are pulled together. Subsequently, the real gas volume will be lower than what's expected by the ideal gas law.
If the pressure becomes extremely high, then the gas molecules are pushed together even further. Under such circumstances, the volume of individual gas molecules becomes significant (Remember that the ideal gas law assumes that the volume of individual gas molecules is insignificant relative to the distance between them). Under such circumstance we can no longer ignore the volume of gas molecules, and this additional volume contributes to the total volume of the gas-->Larger volume relative to what's expected by the ideal gas law.
Ans: less than the calculated pressure, because intermolecular forces reduce the average force of the collisions with a unit area of the container.
Are there any exceptions to the kinetic molecular theory I'm missing? I totally don't understand the reasoning behind this. Can someone please elaborate?
. The answer is:
