Question

For the chemical equilibrium, $CaC{O}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+C{O}_2\left(g\right),\Delta H^{.}$,can be determined from which one of the following plots

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

For the reaction,

$CaCO\rightleftharpoons CaO+CO$

$K+P_{C{O}_2}$ and $K=\left[CO\right]$

($\because \left[CaCO\right]=1$ and $\left[CaO\right]=1$ for solids)

According to Arrhenius equation we have

$K=A{e}^{\frac{-\Delta H_r^0}{RT}}$

Taking logarithm, we have

$log{K}_p=logA-\frac{\Delta H_r^0}{RT\left(2.303\right)}$

This is an equation of straight line. When $logK$ is plotted against $\frac{1}{T}$ we get a straight line.

The intercept of line = $logA$, slope = $-\frac{?H^0}{2.303R}$

Knowing the value of slope from the plot and universal gas constant R, $?H^0$ can be calculated.

(Equation of straight line: $Y=mx+C$. Here,

$log{K}_p=-\frac{\Delta H_r^0}{2.303R}\left(\frac{1}{T}\right)+logA$

Y m x C