C2H4Br2 + 3 I- -> C2H4 + 2Br- + I3-
[C2H4Br2]M [I1]M Initial Rate (M/s)
1 0.127 0.102 6.45 x 10-5
2 0.343 0.102 1.74 x 10-4
3 0.203 0.125 1.26 x 10-4
Determine the order of the reaction in C2H4Br2:
To determine the order of the reaction with respect to C2H4Br2, we can use the method of initial rates.
First, we need to choose two experiments where the concentration of C2H4Br2 changes while keeping the concentrations of other reactants constant. Looking at the given data, we can choose experiments 1 and 3 since the concentration of C2H4Br2 changes (0.127 M to 0.203 M) while the concentrations of I- and other reactants remain constant.
Now, we can write the rate equation based on the given balanced chemical equation:
Rate = k [C2H4Br2]^x [I-]^y
where k is the rate constant, [C2H4Br2] and [I-] are the concentrations of C2H4Br2 and I- respectively, and x and y are the orders of the reaction with respect to C2H4Br2 and I-.
Next, we can divide the rate of experiment 3 by the rate of experiment 1, while keeping the concentrations ratio constant:
(Rate3/Rate1) = ([C2H4Br2]3^x [I-]3^y) / ([C2H4Br2]1^x [I-]1^y)
Plugging in the given values:
(1.26 x 10^-4 M/s) / (6.45 x 10^-5 M/s) = (0.203 M)^x (0.125 M)^y / (0.127 M)^x (0.102 M)^y
We can cancel out the rate constant k, as well as the concentrations of I- since they are constant. This equation simplifies to:
(1.26 x 10^-4 M/s) / (6.45 x 10^-5 M/s) = (0.203 M)^x / (0.127 M)^x
Taking the ratio of the rates gives us:
1.96 = (0.203 M / 0.127 M)^x
Taking the logarithm of both sides:
log(1.96) = x * log(0.203 M / 0.127 M)
Using a calculator:
x = log(1.96) / log(0.203 M / 0.127 M)
Calculating this expression will give us the value of x, which represents the order of the reaction with respect to C2H4Br2.