Assuming enthalpy of combustion of hydrogen at 273 K is -286 kJ and enthalpy of fusion of ice at the same temperature to be +6.0 kJ, calculate enthalpy change during formation of 100 g of ice.

Options

A. `+1622 kJ`
B. `-1622kJ`
C. `+292kJ`
D. `-292kJ`

Answer

B

Explanation

(I) `H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l),Delta_(c)H=-286kJ`
(II) `H_(2)O(s)tounderset(18g)(H_(2)O)(l),Delta_(fus)H=+6kJ`
On subtracting (II) from (I), we get
`H_(2)(g)+(1)/(2)O_(2)(g)to H_(2)O(s)`
`DeltaH=-286-6=-292kJ`
`because`On formation of 18 g of ice, change in enthalpy=-292 kJ
`therefore`On formation of 100 g of ice, change in enthalpy
`=-(292xx100)/(18)=-1622kJ`