Two flasks with identical volumes are connected via a glass tube (the volume of

Question

Two flasks with identical volumes are connected via a glass tube (the volume of the tube is negligible). The flasks are filled with 0.7 mol of N2(g) in total and the

whole system is isolated from the surrounding. Both of the two flasks are initially at 300 K, 50 kPa; then, the temperature of one flask is increased to 400 K while that of the other one remains unchanged (as shown in the figure below). After the system equilibrates: (1) What is the amount of N2(g) (in mole) in each flask? (2) What is the pressure inside the flasks at 400 K?

Explanation / Answer

Initially both flasks were at 300K and contain a total of 0.77 moles of an N2.

Volumes is constant, P varies directly with T.

At equilibrium, each flask has (0.7/2) moles of N2

Ideal Gas Equation:

                                             PV=nRT

Where, P= pressure = 50kPa

R= e Ideal Gas Constant = 0.082

n= number of moles of gas = 0.7/2

T= temperature = 300 K

V = volume= ?

Putting these values in equation

                                             50*V = (0.7/2)*0.082*300

                                             V = 0.1722 L

One flask is heated to the temperature of 400 K, a number of total moles are kept constant at 0.7 moles, but leaking from the flask to the other one will occur,

for example X mol, leaving the flask

Flask A (Heated to 400 K) has [(0.7/2) – X] mole of N2,

and the Flask B (at 300 K) [(0.7/2)+ X] mol. of N2,

As temperature changed pressure in flask will also change.

Let new pressure P’

Now for Flask A

P’V = nRT

P’x V = [(0.7/2) – X] x R x 400………………………………..(1)

Flask B

P’x V = [(0.7/2) + X] x R x 300……………………………………(2)

Now, (1)/(2)

[(0.7/2) – X] x R x 400== [(0.7/2) + X] x R x 300

X = 0.05

N2 in Flask A is 0.3 Moles while in Flask B is 0.4 mole

b. Considering the heated flask, P’V = nRT => P x0.1722 = 0.3 x 0.082 x 400

                                                                        P’ =57.14 kPa

pressure inside the flask at 400 K is 57.14 kPa

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.