For the chemical equilibrium, CaCO3(s) ⇌ CaO(s) + CO2(g),ΔH.,can be determined from which one of the following plots
For the reaction,
CaCO ⇌ CaO + CO
K + PCO2 and K = [CO]
(∵ [CaCO] = 1 and [CaO] = 1 for solids)
According to Arrhenius equation we have
K = Ae−ΔH0rRT
Taking logarithm, we have
log Kp = log A − Δ H0rRT(2.303)
This is an equation of straight line. When log K is plotted against 1T we get a straight line.
The intercept of line = log A, slope = −?H02.303 R
Knowing the value of slope from the plot and universal gas constant R, ?H0 can be calculated.
(Equation of straight line: Y = mx + C. Here,
log Kp = −ΔH0r2.303 R(1T) + log A
Y m x C