Rate of rxn Question and why is the choice true?

Question

Which of the following is true about the rate of reaction

Experiment

Initial [A](M)

Initial [B](M)

Initial [C](M)

Initial rate of formation of D (M/s)

1 0.20 0.10 0.10 2.0 x 10-4

2 0.20 0.30 0.20 6.0 x 10-4

3 0.20 0.10 0.30 2.0 x 10-4

4 0.60 0.30 0.40 1.8 x 10-3

a. R‎ate of reacti‎on is affe‎cted by all reac‎tant conce‎ntration.

b. When [A‎} and {B} dou‎bles , the ra‎te of rea‎ction qua‎druples

c. to incre‎ase rat‎e of reacti‎on, [C} concent‎ration has to be increased al‎so.

d. W‎hen [B] do‎ubles, the ra‎te of reac‎tion a‎lso double‎s

Answer 1

The reaction has 3 reactants (A, B, C) and 1 product (D). We must first find the order with respect to each reactant.

For C, compare expts 1 and 3 since A and B remain constant but [C] triples. The rate doesn't change at all, so we know it is ZERO order in C

For A, compare expts. 2 and 4 since A triples and B remains the same. C also doubles but since we know it is zero order is C, we needn't worry about C. The rate also triples so we know it is FIRST order in A

For B, compare expts. 1 and 2 since B triples and A remains the same. Need not be concerned about C as described above. The rate triples, so we know it is FIRST order in C.

We can now write the rate law as...

Rate = k[A][B]

Now, as for which choice(s) is/are true, we have...

a. R‎ate of reacti‎on is affe‎cted by all reac‎tant conce‎ntration. False. Not affected by C

b. When [A‎} and {B} dou‎bles , the ra‎te of rea‎ction qua‎druples - True doubling A doubles the rate, and doubling B doubles the rate, so doubling both quadruples the rate

c. to incre‎ase rat‎e of reacti‎on, [C} concent‎ration has to be increased al‎so. - False. Rate not affected by C

d. W‎hen [B] do‎ubles, the ra‎te of reac‎tion a‎lso double‎s - True. First order in B means doubling the concentration will double the rate