Which of the following does not have zero entropy at absolute zero?
CO,NO,NaCl,CO2
Answer i have is CO and NO .Please explain.
Some more species not having zero entropy at absolute zero are N2O, water, hydrogen, deuterium and ethane (overall, there are too many). There is not one single reason for all of these cases. For CO, the reason appears to be the random orientation in solid. Energetically, there hardly is any difference between the two arrangements:
CO CO CO CO CO CO....... (I)
CO OC CO OC CO OC....... (II)
The second case is not like a perfect crystal which the third law of thermodynamics requires. Since, the arrangements (I) and (II) are equiprobable, this results in overall disorder not letting entropy become zero at absolute zero.
Thank You sir.