Question

Select the option in which heat evolved is maximum.
Given : `Delta_(f)H^(@) (CO_(2), g) = -75 k Cal//mol, " " Delta_(f)H^(@) (CO, g) = -25 k Cal//mol`
The product will be `CO` if excess amount of carbon is present and `CO_(2)` if excess `O_(2)` is present
A. 10 moles of carbon and 4.5 moles of `O_(2)`
B. 24 gm of carbon and 64 gm of `O_(2)`
C. 4 moles of carbon and 3.5 moles of `O_(2)`
D. 30 gm of carbon and 80 gm of `O_(2)`

Answer 1

Correct Answer - C
(a) `{:(C,+,1/2 O_(2) rarr,CO),(10,,4.5 (L.R.),0),(,,,9):}`
energy released `=9xx-25=-225`
(b) `{:(C,+,1/2 O_(2),rarr,CO_(2),),(2,,2,,0,),(L.R.,,1,,2,DeltaH=-50),(CO+1/2 O_(2) rarrCO_(2),,,,,DeltaH=-100):}`
`{:(2,,1,,2):}`
Total `DeltaH=-150`
(C) `{:(C,+,1/2O_(2),rarr,CO,),(4,,3.5,,0,),(L.R.,,1.5,,4,DeltaH=-25xx4=-100),(,,,,,),(CO,+,1/2O_(2),rarr,CO_(2),),(4,,1.5,,0,),(,,L.R.,,3,DeltaH-3xx50=-150),(,,,,,"Total "DeltaH=-250):}`
(D) `{:(C,+,1/2O_(2),rarr,CO,),(2.5,,2.5,,0,DeltaH=-25xx2.5=62.5),(L.R.,,1.25,,2.5,),(,,,,,),(CO,+,1/2O_(2),rarr,CO_(2),),(2.5,,1.25,,0,DeltaH=-2.5xx50=125),(0,,,,2.5,),(,,,,,"total "DeltaH=62.5+125=187.5):}`