Calculate `DeltaH^(@)` for the reaction
`Na_(2)O(g)+SO_(3)(g)toNa_(2)SO_(4)(s)`
Given the following
`(i) Na(s)+H_(2)O(l)toNaOH(s)+(1)/(2)H_(2)(g)`, `DeltaH^(@)=-146 kJ`
`(ii) Na_(2)SO_(4)(s)+H_(2)O(l)to2NaOH(s)+SO_(3)(g)`, `DeltaH=+418 kJ`
`(iii) 2Na_(2)O(s)+2H_(2)(g)to4Na(s)+2H_(2)O(l)`, `DeltaH=+259kJ`

Options

A. `+823 kJ`
B. `-581 kJ`
C. `-435 kJ`
D. `+531 kJ`

Answer

B

Explanation

`2Na_(2)O+2H_(2)to4Na+2H_(2)O`, `DeltaH=+259kJ`
`2[SO_(3)+2NaOHtoNa_(2)SO_(4)+H_(2)O`
`DeltaH=-2xx418=-836 kJ`
`4[Na+H_(2)OtoNaOH+(1)\(2)H_(2)`
`DeltaH=-4xx146=-584 kJ`
`2Na_(2)O+2SO_(3)to2Na_(2)SO_(4)`
`DeltaH=-1170`
`:. Na_(2)O+SO_(3)toNa_(2)SO_(4)`,
`DeltaH=(-1161)/(2)=-580.5 kJ`