Chemistry - Real Gas Question with Solution | TestHub
A gas X behaves ideally at its Boyle temperature in the pressure range 0 to 40 atm, and its critical temperature is -73°C. Assuming the gas obeys the van der Waal's equation over the entire range of pressure and temperature, which of the following statement(s) must be incorrect regarding the molar volume of the gas?
Options:(select one or more)
Answer:
Solution:
Tc = 200 K, so TB = 27Tc/8 = 675 K = 402°C; the gas is ideal only at 402°C in 0-40 atm. (a) At 200 K (= Tc < TB), Z < 1, so V < RT/P = 20 l: incorrect. (b) At 402°C and 0.821 atm (inside the ideal range), V = 0.0821 × 675/0.821 = 67.5 l: correct, so this is not an incorrect statement. (c) At 402°C the ideal value is 675 ml, but 82.1 atm lies beyond 40 atm where higher-order terms make Z > 1, so V > 675 ml, not 650 ml: incorrect. (d) At 402°C and 0.821 atm, V = 67.5 l, not 6.75 l: incorrect. Hence (a), (c), (d).
