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# Rate Law and Rate Constant

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Question 1. Write the rate law and give the rate constant for this reaction.

2 ClO2(aq) + 2 OH^-(aq) ---> ClO-3(aq) + ClO2^-(aq) + H2O(l)

The following rate data were collected:

Experiment----------[ClO2]---------[OH-]-----------initial rate
1----------------------0.060M-------0.030M--------0.0248 M/s
2--------------------- 0.020M-------0.030M--------0.00276 M/s
3----------------------0.020M-------0.090M--------0.00828 M/s

Question 2. Several experiments for the reaction A + B + 2C ----> products gave these results

Experiment ------Initial [A]-------Initial [B]-----Initial [C]--------- Initial rate
1------------------ 0.20 M---------0.40 M--------0.10 M-----------1.2 M/s
2 ------------------0.20 M --------1.60 M -------0.10 M------------4.8 M/s
3-------------------0.20 M---------0.80 M-------0.20 M------------9.6 M/s
4 ------------------0.40 M---------0.80 M-------0.20 M------------9.6 M/s
5-------------------0.20 M---------0.40 M-------0.30 M------------10.8 M/s

Find the order with respect to A. Find the order with respect to B. Find the order with respect to C. When you find each order, you must state which two experiments you are using to find that order. Find the rate constant.

https://brainmass.com/chemistry/chemical-kinetics/rate-law-rate-constant-531206

#### Solution Preview

Q1: From 2 to 1, there is 3 fold increase in [ClO2], the initial rate increases 9.00 folds. Therefore, the rate is proportional to [ClO2]^2
From 3 to 2, there is 3 fold increase in [OH-], the initial rate increases 3 ...

#### Solution Summary

The expert examines rate laws and rate constants.

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## Kinematics: Rate Law and Rate Constant

Consider the reaction of peroxydisulfate ion S2O8 ^2 - with iodide ion (I-) in aqueous solution:
S2O8^2-(aq) + 3I-(aq)  2SO4 ^2-(aq) + I3-(aq)
At a particular temperature the initial rate of disappearance of S2O8^2- varies with reactant concentrations in the following manner:
Experiment [S2O8 2-] (M) [I-] (M) Initial Rate (M/s)
1 0.018 0.036 2.6 × 10-6
2 0.027 0.036 3.9 × 10-6
3 0.036 0.054 7.8 × 10-6
4 0.050 0.072 1.4 × 10-5

(a) Determine the rate law for the reaction and state the units of the rate constant.
(b) What is the average value of the rate constant for the disappearance of S2O8^2- based on the four sets of data?
(c) How is the rate of disappearance of S2O8^2- related to the rate of disappearance of I-?
(d) What is the rate of disappearance of I- when S2O8^2- =0.025M and [I-] = 0.050 M?

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