Question

Tính Q_p, Q_v ở 25^oC của các phản ứng:

a) CH₄(k) + 2O₂(k) = CO₂(k) + 2H₂O(h)

b) C(grafit) + CO₂(k) = 2CO(k)

Answer 1

a) CH₄(k) + 2O₂(k) = CO₂(k) + 2H₂O(h)

Q_p=\(\Delta\)H₂₉₈=\(\Delta\)H_CO2,k+2\(\Delta\)H_H20,h-\(\Delta\)H_CH4,k-2\(\Delta\)H_O2,k=-94,052+2.(-57,798)-17,889-0=-191,759( Kcal/mol)

Q_v=\(\Delta\)U=\(\Delta\)H-RT\(\Delta\)n; \(\Delta\)n=0, suy ra: Q_v=Q_p=-191,759( Kacal/mol)

 

b) C(grafit) + CO₂(k) = 2CO(k)

Q_p=\(\Delta\)H₂₉₈=2\(\Delta\)H_CO,k -\(\Delta\)H_C,gr-\(\Delta\)H_CO2,k=2.-26,416-0-(-94,052)=41,22( Kcal/mol)

Q_v=\(\Delta\)U=\(\Delta\)H₂₉₈- RT\(\Delta\)n =41,22- 1,987. 298. (1)=40,63 (Kcal/mol)