Phosphine, PH_3(g), decomposes according to the equation 4PH_3 (g) rightarrow P_
ID: 478617 • Letter: P
Question
Phosphine, PH_3(g), decomposes according to the equation 4PH_3 (g) rightarrow P_4 (g) + 6 H_2 (g) The kinetics of the decomposition of phosphine at 950 K was followed by measuring the total pressure in the system as a function of time. The data to the right were obtained in a run where the reaction chamber contained only pure phosphine at the start of the reaction. Choose the rate law that describes this reaction. rate = k (P_PH_3) rate = rate = k rate = k(P_PH_3)^-2 rate = k(P_PH_3)^2 Calculate the value of the rate constant and choose the correct units.Explanation / Answer
For the given reaction for the decomposition of PH3,
plot of lnP vs time gives us a straight line, thus the decomposition reaction follows a first order reaction kinetics.
the rate law for the reaction would be,
rate = k[PH3]
rate constant k
k = [ln(168) - ln(151)]/40
= 2.66 x 10^-3 min-1