In: Chemistry
The following reaction is similar to the breathing cycle of plants:
4KO2(s) + 2CO2 (g) ®2K2CO3 (s) + 3O2 (g) Calculate change inH for the above reaction from the following data:
change in H (kcal)
K(s) + O2 (g) ®KO2 (s) -134.0
KOH(s) + CO2 (g) ®KHCO3(s) -33.5
2KHCO3(s) ®CO2(g) + H2O(g) + K2CO3(s) +33.0
2K(s) + 2H2O(g) ®2KOH(s) + H2 (g) -88.0
H2 (g) + 1/2O2(g) ®H2O(g) -57.8
4*[ KO2 (s) -----> K(s) +
O2 (g)
]
DH1 = 4*+134
2*[2KHCO3(s) ------> CO2(g) + H2O(g) + K2CO3(s)] DH2 = 2*+33.0
4*[KOH(s)+ CO2(g) ---> KHCO3(s) ] DH3 = 4*-33.5
2*[2K(s) + 2H2O(g) ---> 2KOH(s) + H2 (g) ] DH4 = 2*-88.0
2*[H2 (g) + 1/2O2(g) ----> H2O(g)
]
DH5 = 2*-57.8
-----------------------------------------------------------------------
4KO2(s) + 2CO2 (g) ---> 2K2CO3 (s) + 3O2 (g) DH =
DH1+DH2+DH3+DH4+DH5
------------------------------------------------------------------------
DH = 4*134+2*33.0+4*-33.5+2*-88.0+2*-57.8
= 176.4 KJ