I totally can't figure out rate mechanisms for whatever reason. A three-step mechanism has been suggest for the formations of carbonyl chloride: Step 1 Cl2 -> 2 Cl(fast, equilibrium) Step 2 Cl + CO -> COCl (fast equilibrium) Step 3 COCl + Cl2 -> COCl2 + Cl (slow) What is the molecularity of the rate determining step? Here since it was multiple choice, I guess bimolecular & got it right, but have no reason why... Here is another When the concentration of A is doubled, the rate for the reaction: 2 A + B-> 2 C quadruples. When the concentration of B is doubled the rate remains the same. Which mechanism below is consistent with the experiment observations? The answer is (it was multiple choice, but I'll just post the correct answer) Step 1: 2A -> D (slow) Step 2: B + D -> E (fast) Step 3: E-> 2 C (fast) So any ideas regarding how I can better understand the concepts so I don't get slammed for the exam?