Chapter 6, Problem 84AE

The gas arsine ${\text{(AsH}}_{\text{3}}\text{)}$ decomposes as follows:

${\text{2AsH}}_{\text{3}}\text{(}g\text{)}\rightleftharpoons \text{2As(}s{\text{)+3H}}_{\text{2}}\text{(}g\text{)}$

In an experiment pure ${\text{AsH}}_{\text{3}}\left(g\right)$ was placed in an empty,rigid, sealed flask at a pressure of 392.0 torr. After 48 hthe pressure in the flask was observed to be constant at488.0 torr.
a. Calculate the equilibrium pressure of ${\text{H}}_{\text{2}}\left(g\right)$ .
b. Calculate $K_{\text{p}}$ for this reaction.