For the chemical equilibrium,
`CaCO_(3)(s) hArr CaO(s)+CO_(2)(g)`
`Delta_(r)H^(ɵ)` can be determined from which one of the following plots?

Options

A.
B.
C.
D.

Answer

A

Explanation

For the reaction,
`CaCO_(3(g))hArrCaO_((g))+CO_(2(g))`
`K_(p)=pco_(2) and K_(C)=[CO_(2)]`
`(because [CaCO_(3)]=1 and [CaO]=1" for solids"]`
According to arrhenius equation we have
`K=Ae^(-Delta H_(r)^(n)//RT)`
Taking logarithm, we have
log `K_(p)=log A-(Delta H_(r)^(@))/(RT(2.303))`
This is an equation of straight line. When log `K_(p)` is plotted against `1//T`. we get a straight line.
The interecept of this line = log A, slope `=-Delta H_(t)^(@)//2.303 R` Knowing the value of slope from the plot and universal gas constant `R,Delta H_(t)^(@)` can be calculated.
(Equation of straight line : `Y=max +C.` Here,
`log K_(p)=-(Delta H_(t)^(@))/(2.303R)((1)/(T))+log A`
`Y" "m" "x" "C`