Calculating a reaction rate?

Rate law reaction..please help?

• This is the last homework problem I have, can someone PLEASE help me with these? (There are multiple parts, but short) Correct answers=10 pts. Thanks in advance! A reaction in which A, B, and C react to form products is zero order in A, one-half order in B, and second order in C. Part I: Write a rate law for the reaction. (Pick one) a.) Rate=k [A] [B]^2 [C]^1/2 b.) Rate=k [B] [C]^1/2 c.) Rate=k [B]^1/2 [C]^2 d.) Rate=k [A] [B]^1/2 [C] Part 2: What is the overall order of the reaction? Part 3: By what factor does the reaction rate change if [A] is doubled (and the other reactant concentrations are held constant)? Part 4: By what factor does the reaction rate change if [B] is doubled (and the other reactant concentrations are held constant)? Part 5: By what factor does the reaction rate change if [C] is doubled (and the other reactant concentrations are held constant)? Part 6: By what factor does the reaction rate change if the concentrations of all three reactants are doubled?

• Answer:

  If it is zero order in "A", "A" does not appear in the rate law eqtn. If "A" is doubled, it has nothing to do with the rate law. If "B" is half-order, "sqrt(B)" is in the rate eqtn. If "B" is increased by some factor like "m" times, the rate increases by sqrt(m) times. If "C" is 2d order, "C^2" is in the rate eqtn. If "C" is increased by some factor like "m" times, the rate increases by m^2 times. This should solve most of your questions. Just think thru it.