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Iodination Of Propanone Coursework Meaning

 

Kinetics of the reaction between propanone and Iodine in acid solution

2

Section 1

Equation for the reaction:

I

2(aq)

+ CH

3

COCH

3(aq)

→ CH

3

COCH

2

I

(aq)

+ H

+(aq)

+ I

¯(aq)

Iodine + Propanone

Iodopropanone + Hydrogen (cation) + Iodide (anion)

Introduction: Chemistry of the reaction:

Propanone and Iodine react together in an irreversible redox reaction to form Iodopropanone.This reaction is catalysed by aqueous Hydrogen ions (protons) produced from the Sulphuricacid. As the reaction proceeds the dark brown colour of Iodine in solution gradually turnscolourless. This is due to the concentration of Iodine in solution decreasing as it is being usedup reacting to produce colourless Iodide ions and the Iodopropanone. I have chosen to monitorthe progress of this reaction by measuring the absorbance value of this colour change in adigital Colourimeter.

Aims:

1). I aim to individually vary the concentrations of 

each

reactant (Iodine and Propanone)including the acid catalyst (Sulphuric acid) in solution and measure its effect on the rate of reaction in Absorbance (Beer-Lambert Law) using Colourimetry. All of data collected will beused to construct line graphs for each concentration of reactant investigated per experiment.Using the trends of these line graphs, the initial rates of reaction method can be used bydrawing tangents from the starting plots of the reaction progress curve to calculate each rateof reaction

(A

/s

-1

 ).

Finally these values of rate of reaction can be plotted against concentrationof the reactant being investigated to deduce the order of reaction with respect to that reactant- this process will be carried out for each reactant.2). Using the orders of reaction and the rate equation, I aim to calculate a mean rate constant(at room temperature). Through addition of reactant orders (

m+n)

the overall order of reactioncan be deduced.Independent Variable(s):-

Concentration of Iodine (in situ)

(mol dm

-3

)

-

Concentration of Propanone

(mol dm

-3

)

-

Concentration of Sulphuric acid

(mol dm

-3

)

Dependent Variable

 –

Absorbance

Kinetics of the Reaction Between Acetone and Iodine Essay

652 WordsMar 8th, 20133 Pages

Experiment A1:
Kinetics of the Reaction between Acetone and Iodine

The key aim of this experiment was to determine the rate equation for the acid-catalysed iodination of acetone and to hence consider the insinuations of the mechanism of the rate equation obtained.

The stoichiometric equation for the reaction between iodine and acetone is below, followed by the rate equation (where x,y,z and k are the values to be obtained):
I2 + CH3COCH3 CH3COCH2I + HI
-d[I2]/dt = k [I2]x [CH3COCH3]y [H+]z

The procedure was performed as follows: For run 1, 20cm3 of acetone, 10cm3 of sulphuric acid and 145cm3 of water was added to a conical flask. 25cm3 of iodine was then added to this solution which started the reaction and immediately, 20cm3…show more content…

For run 1: (5-5.5)/(7.9-6) = -0.263
For run 2: (7-9)/(14-9) = -0.4
For run 3: (5.5-10)/(17-9) = -0.563

The equation of the line in run 1 between the two points is y – y1 = m(x – x1) y-4.4=-0.263(x-10) therefore y = 0.263x + 1.77

The ratio between the gradients for run 1 and run 2 is 1:2 as 0.4/0.263 is approximately half, whereas the gradient for runs 2 and 3 is 3:2 as 0.563/0.4 is approximately 1.5.

Initial concentration of iodine in run 1:
Using M1V1=M2V2
Initial undiluted conc of iodine = 0.05M and volume of undiluted

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