Question

A sample of gas occupies a volume of 69.9 mL. As it expands, it does 135.3 J of work on its surroundings at a constant pressure of 783 torr. What is the final volume of the gas?

Answer 1

A sample of gas occupies a volume of 69.9 mL. As it expands, it does 135.3 J of work on its surroundings at a constant pressure of 783 torr. What is the final volume of the gas?

This is pressure volume work

Work done = - p delta V

Delta V = v ( final ) – V ( initial )

We convert pressure to atm

Pressure in atm = 783 torr * 1 atm / 760 torr = 1.03 atm

Also volume to L

= 69.9 mL * 1 L / 1000 mL

= 0.0699 L

Work to L atm

= 135.5 J * 0.009869 L atm / 1 J

=1.34 L atm

Lets plug given value in order to get final volume

• 1.34 L atm = - 1.03 atm ( V final – 0.0699L )

1.34 L atm =( 1.03 atm * V final )– (0.072L atm )

1.03 atm * Vfinal = 1.42 L atm

V final = 1.371 L

final volume = 1.371 L