Kinetics of the Crystal
Violet-Sodium Hydroxide
Reaction
REBECCA FORLOINE
LAB PARTNER: DANA
MARCH 24, 2015
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Abstract
The purpose of this lab was to determine the kinetics of the crystal violet - sodium
hydroxide reaction.
We had previously studied thermodynamics which would allow us to predict
if a reaction would be spontaneous and whether the reaction would be endothermic or
exothermic.
While this was useful information, it didn’t give any indication to the rate at which
a spontaneous reaction would occur.
The most important results obtained from this lab was the
ability of students to determine the kinetic rate law for a chemical reaction. This experiment
demonstrated how the rate constant and activation energy of a chemical reaction could be
determined from graphical methods.
The major impact of this work was showing students how
to manipulate a rate low to solve for the constant, concentrations, or order of reaction.
Introduction
The rate of a chemical reaction is the change in concentration of a reactant or prudct as a
function of time.
The rate law establishes the proportionality between the rate of a reaction and
the concentration of reactants.
For a reaction A+BC, the rate law is given as: Rate=k[A]
m
[B]
n
.
Activation energy is the energy required to start a chemical reaction and can be derived from the
Arrhenius equation which is stated as follows:
k
=
−
E
a
RT
lnA
The general goals of this experiment were to use the isolation method to determine the
variables k, m, and n which are the rate law constant, the order with respect to CV, and the order
with respect to hydroxide respectively.
They can be seen in the following rate law for the
following reaction under study.
−
¿¿
n
O H
¿
CV
¿
m
¿
Rate
=
k
¿
To do this the concentration of one of the reactants was set very high relative to the other
so that its concentration did not change too much over the course of the reaction.
This helped us
find n and m based on which reactant was set at a high concentration.
