Question

A fixed quantity of gas at 21 C ehxhibits a pressure of 752 torrand occupies a volume of 5.12 L. a) Calculate the volume the gas will occupy if the pressure is increased to 1.88 atm while the temperature is held constant.b) Calculate the volume the gas will occupy if the temperature is increased to 175 C while the pressure is held constant.

Answer 1

Initial parameters

T = 21 ⁰C = 294 K

P = 752 Torr = 752 / 760 atm = 0.989 atm

V = 5.12 L

R = gas constant = 0.0821 L atm / mol K

Let us calculate initial moles by using ideal gas equation

PV =nRT

n = moles = PV / RT = 0.989 X 5.12 / 0.0821 X 294 = 0.21 moles

(a) on increasing pressure from 0.989 atm to 1.88 atm , at constant temperature

the volume will decrease inversely

P1V1 =P2V2

0.989 X 5.12 = 1.88 X V2

V2 = 2.69 L

b) At constant pressure

V1/T1 = V2/T2

T2 = 175 C= 448 K

5.12 / 294 = V2 / 448

V2 = 7.8 L