Calculate the amount of heat evolved during the complete combustion of 100 ml of liquid benzene from the following data. Predict your answer as (Delta H)/(100) ( in KJ/mol). (i) 18 gm of graphite on complete combustion evolve 585 KJ heat (ii) 15540 KJ heat is required to dissociate all the molecules of 1 litre water into H_(2) and O_(2). (iii) The heat of formation of liquid benzene is 48 kJ/mol (iv) Density of C_(6)H_(6)(l)=0.87 gm//ml

Calculate the amount of heat evolved during the complete combustion of

1.	Calculate the amount of heat evolved during the complete combustion of 100 ml of liquid benzene from the following data. Predict your answer as (Delta H)/(100) ( in KJ/mol). (i) 18 gm of graphite on complete combustion evolve 585 KJ heat (ii) 15540 KJ heat is required to dissociate all the molecules of 1 litre water into H_(2) and O_(2). (iii) The heat of formation of liquid benzene is 48 kJ/mol (iv) Density of C_(6)H_(6)(l)=0.87 gm//ml
Answer» Solution :`(i)""C(s) + O_(2)(G) rarr CO_(2)(g) , DeltaH_(f)^(0) = -390KJ//mol, "" DeltaH_(f)^(0) = (585)/(18)xx12` `(ii) "" H_(2)(g)+(1)/(2)O_(2)(g) rarr H_(2)(l) , DeltaH_(f)^(0) =-280 KJ//mol ,"" Delta H_(f)^(0) = (15540)/(55.5)` `(III)"" C_(6)H_(6)(l) + (15)/(2)O_(2)(g) rarr 6CO_(2)(g) + 3H_(2)O(l) ,"" DeltaH_(f)^(0) = -48` `THEREFORE""DeltaH^(0) = [6(-390) + 3(-280)] - 48 = -3228 KJ//mol` `""` Mass of benzene is `= 0.87 xx 100 = 87g` `therefore""` Heat evolved from `87` gm benzene `=3600KJ` `""` Hence , `(DeltaH)/(100)=36KJ.`