Question

How to differentiate between condensable and non condesable gases ?
For example we have a process for benzene and methane production be reacting hydrogen and tolune , we would like to find the boiling point for toluene and benzene so the professor considered toulene and benzene as a condensable gases why ?

Answer 1

DIfferentiation of condensables and non condensable gases is quite simple.

Actually one can take or consider some of the compounds as condensibles or non condensibles based on their experience. One has to have certain experience in assessing whether a particular compound is in which state.

However, having information of Temperature and pressure of that particular material decides the state of matter. For simplicity we can take water. Water is solid at <0 ⁰C and 1 atm. At same pressure, water is liquid at >0 ⁰C. and it is vapor (gas) at >100 ⁰C. If you alter the pressure, let us say at less than 1 atm water starts boiling and becoming gas at less than 100 ⁰C. If you increase the pressure water will boil at > 100 ⁰C. Let us see the table.

So, It is all pressure and temperature which decides the states of matter. So, you professor would have considered some of the compounds as condensible some as the non condensible based on his experience. Even methane can be converted to liquid around -160 ⁰C. Your reaction conditioned might not that low. So he would have considered methane as non condensible.