This isn't a homework question per se, but it is from a (graduate) textbook. I'm not taking a course in this, but I've been trying to learn some basic chemical kinetics and couldn't find other problems like this one. 1. The problem statement, all variables and given/known data The rate of the reaction CH5NH2(g) -> C2 H4(g) + NH3(g) is measured by noting Ptotal as a function of time. At 500 degrees celsius, the following results were obtained: Time (sec): 0 60 360 600 1200 1500 Ptotal (mm Hg): 55 60 79 89 102 105 a: Find the order of the reaction. b: Find the specific rate constant. 2. Relevant equations 3. The attempt at a solution At first, I thought that this was a straightforward question asking me to use the integrated rate equations and graphing to find k, but then I noticed that, although pressure can be substituted for concentration (I think?) in this case, what was measured isn't the decrease in reactant, but rather increase in product. However, I don't understand the importance of the pressure of 55 mm Hg at t=0. I suppose I can't just use the difference between two Pts as x, the decrease in reactant. It's been a while since I've taken general chemistry, so any help is appreciated.