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Individual investigation - Reaction to be studied Rate of reaction between propanone and iodine

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Reaction to be studied Rate of reaction between propanone and iodine proceeds in acidic solution (H+ ions as a catalyst). CH3COCH3 (aq) + I2 (aq) ? CH3COCH2I (aq) + H+ (aq) + I - (aq) Propanone Iodine Iodopropanone I have to investigate: > The effect of changing the concentrations of the reactants (including the catalyst) on the rate of reaction. > The order of each reactant. > Therefore, find out the rate equation. > Different methods to see the effects on the rate of reaction. > The effects of temperature on rate of reaction. > Therefore, find out the activation enthalpy for the reaction. > The effect of other acidic catalyst on rate of reaction. > The effects of temperature with the new catalyst on rate of reaction. > Therefore, comparing the activation enthalpy with and without the catalyst. CHEMICAL KNOWLEDGE: Collision theory: Different factors affect the rate of reaction such as: > Temperature > Catalyst > Concentrations of reactants According to the collision theory, for a reaction to occur the reactant particles must collide. As the we increase the factors, the particles will collide more vigorously due to which the rate of the reaction increases. Different reactions can happen at different rates. Reactions that occur slowly have a low rate of reaction. Reactions that happen quickly have a high rate of reaction (reactant's bond are broken faster and new bonds are made faster). But particles with only little energy will not react when they collide. Therefore, for a reaction to take place particles must collide with enough energy (Activation Energy). > Temperature: As we increase the temperature, the kinetic energy of the particles increases so they collide more and vibrate more resulting increase in rate of reaction. Increasing temperature increases number of particles with minimum required activation energy. The area under a curve shows the number of particles. At the higher temperature curve shifts to the right (which is T+t) ...read more.


10) 5 seconds before next sampling time, remove the test tube from the beaker and dry it (with tissue) and take the reading. 11) Repeat the highlighted steps up to maximum of 4 minutes. 12) After the maximum time, take the reading of final temperature of the solution. 13) Repeat the steps from step 4 to step 12 for different temperature. METHODS FOR EXPERIMENT 4: AFFECT OF CATALYST ON RATE Catalyst used is Phenol (C6H5OH) Equipment needed: Same equipment as experiment 2 Method: Similar method as the experiment 2 but you have to change the concentration of catalyst at given volume. (Table is shown below) Run 1: concentration of Phenol= 0.0010moldm-3 Run 2: concentration of Phenol = 0.0005moldm-3 Run 3: concentration of Phenol = 0.00025moldm-� Run Volume of 2moldm-3 Propanone/cm3 Volume of 0.01 moldm-3 Iodine/cm3 Volume of 2moldm-3 Hydrochloric acid/cm3 Volume water /cm3 Volume of phenol/cm3 Total volume/cm3 1 1.00 2.00 2.00 4.00 1.00 10.00 2 2.00 2.00 2.00 3.00 1.00 10.00 3 4.00 2.00 2.00 1.00 1.00 10.00 METHODS FOR EXPERIMENT 5: AFFECT OF CATALYST ON RATE WITH TEMPERATURE Equipment needed: Same equipments as experiment 3 Method: Similar method as experiment 3 but you have to change volume of water (subtract 1 cm3 because you are adding 1 cm3 of catalyst (phenol). ANALYSIS AND RESULTS FOR EXPERIMENT 1: QUENCHING In this experiment, we have to find out the titre volume so that we can find the concentration of the iodine giving us the idea of how the concentration of iodine varies the time. The purpose of this experiment was to monitor the reaction identifying the colour change. In this experiment the colour changed from dark blue (because the starch was added to the reaction mixture) to the colourless which was the end point. . Time/(minutes and seconds) Initial reading/ cm3 Final reading/ cm3 3.04 0.00 4.00 6.01 4.00 7.80 9.10 7.80 10.9 > Observations: At the beginning, iodine was orange/brown colour. ...read more.


Equipment should not pose much of a threat in causing error at worst for titration volume 13.70cm3 the volume will be off (due to equipment) by approximately �0.20cm3. 10cm3 volumetric pipette 'class B' (0.04/10cm3) x 100 = 0.40% 25cm3 volumetric pipette 'class B' (0.06/25cm3) x100 = 0.24% 50cm3 volumetric pipette 'class B' (0.10/ 50cm3) x 100 = 0.20% Overall error for diluting 0.02moldm-3 sodium thiosulphate using 1 litre volumetric flask 'class B'. Using volumetric pipettes (((2 x 0.12) + (0.10))/250) x 100 = 0.136% Using volumetric flask (0.8/1000) x 100 =0.08% Overall error= 0.136% + 0.08% = 0.216% Overall, the equipment error is not a huge factor affecting values given for titration volumes mainly applying to larger volumes. Human errors/ other errors: * A 'readymade' from the lab solutions. I could have made the solution myself. * There may be contamination in the equipments that I use like conical flasks/ beakers/ dropper pipette. I could have use a new equipment or rinse the equipment properly with the solution that I will be going to use. * Delaying when taking the time . I could have asked my friend, to start the stop clock as I pour the propanone to iodine-HCL mixture. * Determining the end point of the reaction. I could have used clean white tile under the conical flask which would let me see the colour clearly. Most human error is when I have to determine the end point which is hard to tell. For Colorimetry From the table above it is clear that the graduated pipette is up to 10 times more accurate than the dropper pipette. Human errors/ other errors: * Same as in titration. For temperature: Human errors/ other errors: * Same as above experiment. * Make the temperature constant because it is very hard to make the temperature same for the reaction. I should have used a water bath to make the temperature more stable/constant. REFERENCE: http://www.chemguide.co.uk/physical/basicrates/temperature.html Effect of temperature on the reaction rates: http://en.wikipedia.org/wiki/Collision_theory Collision theory: ?? ?? ?? ?? ...read more.

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