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The standard enthalpy of formation of am...

The standard enthalpy of formation of ammonia gas is
Given: `N_(2)H_(4) (g) + H_(2) (g) rarr 2NH_(3) (g), Delta H_(r)^(@) = - 40 kJ//mol`
`DeltaH_(f)^(@) [N_(2)H_(4) (g)] = - 120 kJ//mol`

A

`-60`

B

`-180`

C

40

D

`-80`

Text Solution

Verified by Experts

The correct Answer is:
D
`Delta_(r)H^(@)= sum_(i) a_(i) Delta_(f) H_("(products)")^(@)-sum_(i) b_(i) Delta_(f) H_("(reactants)")^(@)`
`-40=2Delta_(f) H^(@)+120`
`Delta_(f)H^(@)=-80`
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