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Gases
Air Density     

The air in a hot-air balloon at xxx torr is heated from T1 to T2. Assuming that the moles of air and the pressure remain constant, calculate the density of the air at each temperature. (The average molar mass of air is yy.y g/mol.)

Prepare a complete calculation plan using words, symbols, units, etc. that would be applied to solve the problem IF numerical values were available.


Gases can be compressed because

 (a) gas molecules are in constant motion.
 (b) gas molecules move in straight lines between collisions with the walls of the container.
 (c) the size of a gas molecule is very small compared to the space between molecules.
 (d) there are no forces of attraction between gas molecules.
 (e) gas molecules slow down when they become cooler.


Which will always decrease the volume of a sample of methane gas which occupies a volume of 2.4 L at 25 °C.

 (a) An increase in pressure and an increase in temperature.
 (b) A decrease in pressure and a decrease in temperature.
 (c) An increase in pressure and a decrease in temperature.
 (d) A decrease in pressure and an increase in temperature.


The volume of a sample of gas at constant temperature was measured at 4 different pressures.  Which set of data was measured incorrectly?

 (a) P = 2.0 atm; V = 24.0 mL
 (b) P = 1.6 atm; V = 27.7 mL
 (c) P = 1.4 atm; V = 34.3 mL
 (d) P = 1.2 atm; V = 40.0 mL
 (e) It is impossible to tell unless n and T are known.

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