Chemistry 112
Third Hour Exam
Name:____________
(4 points)
Please show all work for partial credit
All problems worth 14 points. You only have to answer 7 of the 8 questions!
If you attempt all 8 I will give you your 7 best scores.
1A. According to a source I found on the web, the cabin pressure in a commercial airliner
cannot go below 1,572 lbs/ft2, the pressure found at an altitude of 8000 ft above sea level.
Convert 1572 lbs/ft2 to atm.
1B. According to a second source I found on the web, a research group experimentally
determined the pressure found on several different flights. According to this paper the
average cabin pressure was found to be 846 hPa. Convert 846 hPa to atmosphere, and
tell me if the airlines are within their legal limits. (Since an h is not one of the units I had
you memorize, I will give you that 1 h or 1 hecto = 1x102)
2. I am going to fill a 2 L balloon with helium at Walmart where the pressure is .89 atm and
the temperature is 21o C (~70oF). I am going to release the above balloon at the top of
Harney peak where the pressure is 600 torr and the temperature is 5o C (41oF). What is
the volume of the balloon now?
2
3. I have 2g of H2 gas in one balloon and and 28g of N2 gas in another balloon. If both
gases are at STP:
Circle one
A. Which gas has the larger volume?
He N2
both are the same
B. Which gas has the higher pressure?
He
N2
both are the same
C. Which gas has the higher density?
He
N2
both are the same
D. Which gas has the higher Kinetic Energy?
He
N2
both are the same
E. Which gas has the higher uRMS?
He
N2
both are the same
If a connection is made between the balloons so the gases can mix with each other:
F. Which gas will have the higher partial pressure in the mixture?
He N2
both are the same
G. Which gas will have the higher mole fraction?
He
N2
both are the same
4. True of False
_______
For an ideal gas, PV/nRT = 1
_______
Many gases are non-ideal at low pressure and high temperature.
_______
Many gases are non-ideal at high pressure and low pressure.
_______
Non-ideality effects come about because gas molecules can interact.
_______
Non-ideality effects come about because gas molecules have a volume.
_______
Non-ideality effects come about because gas molecules can be compressed.
_______
The theory that predicts non-ideality in gases was invented by Dalton.
3
5. As a system increases in volume it absorbs 52.5J of energy in the form of heat from the
surroundings. The piston is working against a pressure of 0.500 atm. The final volume of
the system is 58.0L. What was the initial volume of the system if the internal energy of the
system decreased by 101.0J?
6. If it takes 1000 J of energy to raise the temperature of a 150g block of metal from 273K
to 290K, what is the specific heat capacity of the metal?
4
7. Define the following terms:
Mole fraction
Urms
STP
Molar heat capacity
ÄHfo
Enthalpy
wavelength
8. Some of the experiments proposed for the Homestake Mine involve neutrinos. While
nobody has measured the mass of a neutrino, it is thought that the heaviest neutrino is
about ~ 9x10-37 kg. (1 million times smaller than the mass of an electron.)
Assuming that a neutrino travels at 95% the speed of light, what is the wavelength
and energy of the waveform associated with a neutrino?