Question
Initially there are 3 weights, each weighing 1500 kg on themoveable piston. The radius of the piston is 1 meter and theinitial height is 1 meter. At 330 K, how many moles ofhelium would be below the piston, assuming that helium is behavingideally? So far I have found the volume under the piston but then Idon't know how to get moles because you can't use the ideal gas lawbecause you don't know the pressure either. Pleasehelp! Initially there are 3 weights, each weighing 1500 kg on themoveable piston. The radius of the piston is 1 meter and theinitial height is 1 meter. At 330 K, how many moles ofhelium would be below the piston, assuming that helium is behavingideally? So far I have found the volume under the piston but then Idon't know how to get moles because you can't use the ideal gas lawbecause you don't know the pressure either. Pleasehelp! So far I have found the volume under the piston but then Idon't know how to get moles because you can't use the ideal gas lawbecause you don't know the pressure either. Pleasehelp!
Explanation / Answer
Volume of the cylinder , V = r^2 h Where r = radius of the cylinder = radius of the piston = 1m h= height = 1 m So, V = 3.141 m^3 We know that P = Force / area Force = mg =3 * 1500 Kg * 9.8 m/ s Where m = total mass = 3 * 1500 Kg g= acceleration due to gravity = 9.8 m/s^2 Area of the cylinder , A = 2rh =2 * * 1* 1 = 6.282 m^2 Area of the cylinder , A = 2rh =2 * * 1* 1 = 6.282 m^2 So Pressure P = 7018.7359 Pa Given temperature T = 330 K We know that PV = nRT Where V = Volume = 3.141 m^3 P= Pressure = 7018.7359 Pa n= no . of moles = ? R= gas constant = 8.314 J / mol - K Plug the values we get no . of moles of He n= PV / RT = 8.035 moles