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Tuesday, November 01, 2011

Boyle's Law



Boyle's Law


Note. Any convenient units can be used for pressure and volume, provided that the units for P1 are the same as those for P2, and that the units for V1 are the same as those for V2.

(Use g = 9.8 N kg-1)     1 atm =  Atmospheric pressure = 100 000 Pa = 100 000 Nm-2



  1. A fixed mass of gas at constant temperature has a volume of 500 cm2 at a pressure of 1 atm. What will its volume be at a pressure of 4 atm?  125 cm3



  1. A gas has a volume of 600cm3 at a pressure of 3.0 x 105 Pa.  What is its volume at a pressure of 6.0 x 105 Pa?  300 cm3



  1. A gas has a volume of 1000 cm3 at a pressure of 1 atm. At what pressure will it occupy 100 cm3?   10 atm



  1. The pressure exerted by a gas is due to the molecules of the gas bombarding the walls of the container. Why does the pressure increase when the volume is decreased at constant temperature? Less volume, molecules closer together, more collisions etc



  1. A cylinder of compressed air has a volume of 51 cm3 at a pressure of 8 atm. When the cylinder is opened, what volume of air will escape?                                           



P1V1 = P2V2

rearranging V2 = P1V1/ P2           

V2 = 8 x 51/ 1 = 408 cm3 minus the 51cm3 left in the cylinder = 357 cm3

 

  1. A diver is working in sea-water of density 1025 kg m-3 on a day when atmospheric pressure is 100 450 Pa. A bubble from his mask is three times the volume when it reaches the surface. At what depth is he working? 20m



  1. A lake is 92.7 m deep. A bubble at the bottom of the lake has a volume of 0.5 cm3. What will its volume be at the surface if a water barometer would read 10.3 m (i.e. atmospheric pressure is the same as the pressure at this depth)? 5cm3



  1. A uniform cylinder 0.60 m long is sealed at one end. It is lowered open end downwards into a lake so that the mouth just touches the bottom. When retrieved the inside is wet up to 0.50 m from the mouth. Find the depth of the lake if a water barometer would read 10.4 m of water. 52.5m



  1. A cylindrical diving bell 8 m high is lowered into water so that the top of the bell is 0.75 m below the surface. If the atmospheric pressure is the same as that exerted by a column of water 10.25 m high, find how far the water rises inside the bell. 6m



A vessel of volume 500 cm3 containing air at a pressure of 8.0 x 104 Pa is connected by a very narrow tube fitted with a tap, to a vessel of volume 700 cm3 containing air at a pressure of 2.0 x 105 Pa. What is the resulting pressure in the vessels when the tap is opened?                     1.5 x105 Pa



A compression pump is connected to a vessel of volume 500 cm3. For each stroke of the pump the piston sweeps 50 cm3 of air at atmospheric pressure into the vessel. If the initial pressure in the vessel is 1 atm, find the pressure in the vessel after 2 strokes.

1.2 atm



An exhaust pump is connected to a flask of volume 100 cm3. The volume swept out by the piston is 25 cm3 for each stroke. The pressure in the vessel is originally 1 atm. By considering one stroke at a time, find the pressure in the vessel after two strokes. 0.64atm


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