Question

For a hypothetical reaction ,` 3A rarr A_(3)`
`DeltaC_(p) (i n J)=6.0+2.0xx10^(-3)T`
`DeltaH=-20kJ mol^(-1)` at `300K`
The temperature at which reaction neither absorbs nor releases heat is `:`
A. `2557^(@)C`
B. `255^(@)C`
C. `2284^(@)C`
D. `228^(@)C`

Answer 1

Correct Answer - C
`DeltaH_(2)=DeltaH_(1)+int_(T_(1))^(T_(2))C_(p)dT`
`DeltaH_(2)=DeltaH_(1)+int_(300) ^(T)(6.0+2.0xx10^(-3)T)dT`
`=-20000+[6.0T-6.0xx300+1.0xx10^(-3)xxT^(2)-1.0xx10^(-3)xx(300)^(2)]`
`:. 6.0T-1800+1xx10^(-3)T^(2)-90-20000=0`
or`1xx10^(-3)T^(2)+6.0T-21890=0`
or `T=2557K=2284^(@)C`