The heat of combustion of ethanol determinal in a bomb calorimeter is -670.48 K. Cals `"mole"^(-1)` at `25^(@)C`. What is `Delta H` at `25^(@)C` for the reaction :-

Options

A. `- 335.24 " kcal " `
B. `669.58 " kcal "`
C. `- 670.48 " kcal " `
D. `+ 670.48 " kcal " `

Answer

B

Explanation

Experimental determination of heats of reaction by bomb calorimeter represents its value at constant volumem ie, `Deltau`
`therefore Delta U = Delta H - Delta nRT`
`= -(670.48 xx 10^3)-(-1.5 xx 2 xx 298)`
`-669586 cal ` .