2.1 Constant Volume Batch Reactor (CVBR)

Total Pressure Method (for gas phase reactions): \[aA + bB + \cdots \rightarrow rR + sS + \cdots\] The partial pressure of \(A\) (i.e., \(P_A\)) is given by \[P_A = C_A RT = P_{A0}-\frac{a}{\Delta n}(\pi - \pi_0)\] where

\(\Delta n\) = \((r+s+\cdots)-(a+b+\cdots\))
\(P_{A0}\) = partial pressure of \(A\) at initial time
\(\pi_0\) = initial total pressure
\(\pi\) = total pressure at time \(t\)

And, for product \(R\), we have \[P_R = C_R RT = P_{R0} + \frac{r}{\Delta n}(\pi-\pi_0)\] Caution: The ‘total pressure method’ is not to be used when

  1. the precise stoichiometry is not known, or

  2. more than one stoichiometric equation is required to represent the chemical reaction.