Question

4PH3(g) ----> P4(g) + 6H2(g)

Phosphine gas, PH3(g), decomposes on a tungsten surface according to the equation above. The rate of decomposition is measured at high pressures of
PH3, and the results are plotted. At high pressures, what order reaction is the decomposition of PH3?.

Answer 1

The decomposition of PH3 on a tungsten surface at high pressures is a first-order reaction meaning that the rate of the reaction is directly proportional to the concentration of PH3 molecules on the surface.

The graph shows that the rate of the reaction (represented by the slope of the line) is constant at different concentrations of PH3 and is a characteristic of a first-order reaction, where the rate is independent of the concentration of the reactant.

If the reaction were zero-order, the rate would be constant regardless of the concentration of PH3, and the line would be horizontal. If the reaction were second-order, the rate would be proportional to the square of the concentration of PH3, and the line would be curved.