Chemical Thermodynamics Question 248
Question: Calculate the standard heat of formation of carbon disulphide $ (l) $ , given that the standard heat of combustion of carbon $ (s) $ , sulphur $ (s) $ and carbon disulphide $ (l) $ are $ -393.3,,-293.72 $ and $ -1108.76,kJ,mo{{l}^{-1}} $ respectively [Roorkee 1989; BHU 1997]
Options:
A) $ -128.02,kJ,mo{{l}^{-1}} $
B) $ +12.802,kJ,mo{{l}^{-1}} $
C) $ +128.02,kJ,mo{{l}^{-1}} $
D) $ -12.802,kJ,mo{{l}^{-1}} $
Show Answer
Answer:
Correct Answer: C
Solution:
$ C+2S\to CS_2\Delta H=- $
$ C+O_2\to CO_2\Delta H=-393.3kJ $ -.(i) $ S+O_2\to SO_2\Delta H=-293.72kJ $ -..(ii) $ CS_2+3O_2\to CO_2+2SO_2\Delta H=-1108.76,kJ $ -..(iii) eq. (ii) × 2 + eq. (i) - (iv) eq. (iii) - eq. (iv) and find required result .
