Question

A closed vertical cylinder is divided into two parts by a frictionless piston, each part contains
1 mole of air. At 27°C the volume of the upper part is 4 times than that of the lower part. Calculate the
temperature when volume of the upper part will be three times than that of the lower part.​

Answer 1

Answer:

The answer is 421.875 K

Explanation:

Moles are same

P(lower) = P(upper) + P(friction)

Using PvVv = PLVL

P(upper) / P(lower) = 1/4

P(upper) / P(upper) + P(piston) = 1/4

P(piston) = 3P(upper) 1

P(lower final) = P(upper final) + P(piston)

P(lower) / P(upper) = V(upper) / V(lower)

P(upper) + P(piston) / P(piston) = 3

2P(upper final) = 2P(piston)

P(upper final) = 3/2 P(upper initial)

Using PV/T

Balance for upper chamber.

P(upper) x 0.8V / 300 = 3/2 P(upper) x 0.75 V/ Tf

Tf = 3/2 x 3/4 x 300/0.8

   = 421.875 K