12 gram of carbon reacted with oxygen to produce CO and CO2 at 25 degree and at constant pressure.75Kcal heat was liberated and no carbon reacted.calculate the mass of oxygen which reacted.delata Hf(CO)=-24Kcal/mol and deltaHf(C))=-24Kcal

1
by Deleted account

2014-12-05T08:25:50+05:30

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
It looks like the heat of formation values given are probably not right.

2 C +  O2  =>  2 CO        Let us say  a fraction = 2x moles formed CO.
C + O2    => CO2          Then    a fraction 1 - 2x  moles formed CO2.

We are initially given 1 mole (12 gms) of Carbon.  So 2x moles of C and x moles of O2 combine to get 2x moles of  CO.

(1-2x) moles of C combines with 1-2x moles of O2 to give  (1-2x) moles of CO2.

Total enthalpy change from both reactions
= 2x * Hf(CO) + (1-2x) * Hf(CO2) - (x+1-2x) * Hf(O2) - (2x+1-2x) * Hf(C)
= - 75 Kcal = - 75 * 4.18 KJ
2x * (-110.5) kJ +  (1-2x) * (-393.5)  KJ - (1-x) * (0 )  KJ - (+1.88 ) KJ  = - 75 * 4.18 KJ
x = 0.138

Total moles of oxygen reacted =  1 -x  = 0.862
Mass of oxygen reacted = 0.862 * 32 = 27.584 gm