Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

1/ A cylinder 1.00 m tall with inside diameter 0.120 m is used to hold propane g

ID: 2112203 • Letter: 1

Question

1/ A cylinder 1.00 m tall with inside diameter 0.120 m is used to hold propane gas (molar mass 44.1 g/mol). It is initially filled with gas until the gauge pressure is 1.30 x 10^6 Pa and the temperature is 22.0oC. The temperature of the gas remains constant as it is partially emptied out of the tank, until the gauge pressure is 2.50 x 10^5 Pa. Calculate the mass of propane that has been used.


2/ A vertical cylindrical tank contains 1.80 mol of an ideal gas under a pressure of 1.00 atm at 20.0oC. The round part of the tank has a radius of 10.0 cm, and the gas is supporting a piston that can move up and down in the cylinder without friction. (a) What is the mass of this piston? (b) How tall is the column of gas that is supporting the piston

Explanation / Answer

Volume of cylinder V = %u03C0 x (diameter/2)2 x height

= 3.142 x (0.120/2)2 x 1.00 = 0.01131 m3

Temperature = 22 deg C = 295 K

Initial pressure P1 = 1.30 x 106 Pa

Final pressure P2 = 2.50 x 105 Pa

Using the ideal gas equation PV = nRT:

Initial moles of propane n1 = P1V/RT

= 1.30 x 106 x 0.01131/(8.314 x 295) = 5.995 mol

Final moles of propane n2 = P2V/RT

= 2.50 x 105 x 0.01131/(8.314 x 295) = 1.153 mol

Moles of propane used = n1 - n2

= 5.995 - 1.153 = 4.842 mol

Mass of propane used = moles of propane used x molar mass of propane

= 4.842 x 44.1 = 213.5 %u2248 214 g