3. You propose two reaction mechanisms for a reaction you are studying. You experimentally determine that the overall reaction is 1st order with respect to (CH3)3CBr and Oth order with respect to cyanide. Which mechanism(s) is/are valid? Explain your answer. Mechanism A Step 1: (CH3)3CBr (CH3) C++ Br ->>> Step 2: (CH3)3CCN(CH3)3CCN Overall: (CH3)3CBr + CN→ (CH3)3CCN + Br Mechanism B Single-step: (CH3)3CBr +CN (CH3)3CCN + Br 4. On the axes below, draw the energy diagram of a one-step, exothermic reaction with an activation energy of 40 kJ/mol and a AH of -30 kJ/mol. Then, draw another curve corresponding to the reaction in the presence of a catalyst that reduces the activation energy by 20 kJ/mol. 100 80 Energy (kJ/mol) 80 60 40 40 20 20 reactants Reaction progress

For the past 10 years, the unsaturated hydrocarbon 1, 3-butadiene (CH2 = CH - CH = CH2) has ranked 38th among the top 50 industrial Chemicals. It is used primarily for the manufacture of synthetic rubber. An isomer exists also as cyclobutene: The isomerization of cyclobutene to butadiene is first-order and the rate constant has been measured as 2.0104s1 at 150 C in a 0.53-L ?ask. Determine the partial pressure of cyclobutene and its concentration after 30.0 minutes if an isomerization reaction is carried out at 150 C with an initial pressure of 55 torr.

The plot below shows the number of collisions with a particular energy for two different temperatures. a. Which is greater, T2 or T1? How can you tell? b. What does this plot tell us about the temperature of the rate of a chemical reaction? Explain your answer.

For each of the following reaction diagrams, estimate the activation energy (Ea) of the reaction: