Phosphine, PH3(g) , decomposes according to the equation4PH3(g)⟶P4(g)+6H2(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 in the table were obtained in a run where the reaction chamber contained only pure phosphine at the start of the reaction. Time (min)Ptotal (Torr)0.0010040.015180.0168100171