Question

Two tanks (A & B) are filled with carbon dioxide and are initially cut-off from another by means of a closed valve. Tank A has a volume of 1.0 m³, pressure of 90 kPa and a temperature of 350 K. Similarly, tank B has a volume of 0.5 m³, pressure of 200 kPa and a temperature of 460 K.

After opening the valve, both tanks reach a uniform temperature of 390 K. What is the final pressure in both tanks?

Answer 1

Ans :

In Tank A :

volume = 1.0 m3 = 1000 L

p = 90 kPa = 0.888 atm

T = 350 K

Using the ideal gas law , pV = nRT

where = R = 0.0821 L.atm/mol.K

0.888 x 1000 = n x 0.0821 x 350

n = 30.9 moles

In tank B :

p = 200 kPa = 1.974 atm

V = 0.5 m3 = 500 L

T = 460 K

1.974 x 500 = n x 0.0821 x 460

n = 26.1 mol

Total volume = 1.0 + 0.5 = 1.5m³ = 1500 Litre

Total moles = 30.9 + 26.1 = 57 moles

T = 390 K

p x 1500 = 57 x 0.0821 x 390

p = 1.217 atm

= 123.3 kPa

So the final pressure in both the tanks will be 123.3 kPa