Question

6 litres of an ideal gas expands isothermally at a temperature of 300 Kelvin up to 10 litres at a pressure of 5 atm, what is the work done?

(a) 30 Newton metre

(b) 80 Newton metre

(c) 50 Newton metres

(d) 20 Newton metre

This question was posed to me in an international level competition.

This intriguing question comes from Thermodynamics Applications in section Thermodynamics of Chemistry – Class 11

Answer 1

The correct choice is (d) 20 Newton metre

To elaborate: The expression for work done is given by pressure x volume difference, here an ideal gas has a volume difference of 4 litres at 5 ATM pressure. So the work done = 10 – 6 liters  x 5atm = 20 Newton metre.