For a reaction that is first order with respect to [D] and second order with respect to [E], which of the following will result in no change to the overall reaction rate?
A. Double [D] and halving [E]
B. Halving [D] and doubling [E]
C. Double [D] and doubling [E]
D. Increasing [D] by a factor of 4 and halving [E]
Solution: Orders are powers of the reactants in the rate law.
Our rate law would be: Rate= k [D][E]^2
Let's plug in numbers instead of D and E for each answer choice.
A. Double [D] and halving [E]
Rate = 2(1/2)^2= 1/2
B. Halving [D] and doubling [E]
Rate = (1/2)(2)^2 = 2
C. Double [D] and doubling [E]
Rate = 2(2)^2= 8
D. Increasing [D] by a factor of 4 and halving [E]
Rate = (4)(1/2)^2 = 1
No rate change, D must be the answer.