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Lab report introduction to chemical reactions
Lab report introduction to chemical reactions
Lab report introduction to chemical reactions
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Determining the Activation Energy of the Reaction Between Bromide Ion and Bromate Ion in Acid Solution
Objectives:
By reacting Potassium Bromide and Potassium Bromate in the acid
solution in varies temperature, we can then determine the Activation
Energy of the reaction in different temperature through the equation:[IMAGE].
Results:
Experiment Temperature
Time t/s
ln 1/t
Temperature K
1/K
80
≒0
N/A
353
2.83286119*10-3
50
21
-3.044522438
324
3.086419753*10-3
45
27
-3.295836866
316
3.164556962*10-3
40
42
-3.737669618
315
3.174603175*10-3
35
70
-4.248495242
311
3.215434084*10-3
30
113
-4.727387819
304
3.289473684*10-3
Questions:
1. Give an equation for the reaction between phenol and bromine.
[IMAGE]
2. What is the use of methyl orange in this experiment?
The methyl orange is used as an indicator for the reaction. Bromine
will be produces during the reaction and it will react with phenol
rapidly. Once all the phenol is used up, further bromine produced will
bleach the methyl orange immediately. So the rate of the reaction can
be calculated from the time for the indicator to be decolorized.
3. Based on your results, is it advisable to perform the experiment at
high temperatures such as 80℃?
From the above results, the time of the reaction is shorter as the
experiment temperature increase. So it is not advisable to perform the
experiment at high temperatures as the time of reaction is too short,
it is not easy for us to record.
4. Why is it not necessary to know how far the reaction has proceeded
at the point where the methyl red is decolourized?
In the experiment, the number of mole and the molarity of each
chemicals used are the same. And the appearance of the pink colour
only determines that there are some content of the reaction has
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
Procedure: Anisole (0.35mL, 0.0378mol) was obtained and placed in a pre-weighed 25 mL round bottom flask, along with 2.5 mL of glacial acetic acid and a magnetic stir bar. Then the reaction apparatus was assembled, the dry tube was charged with conc. sodium bi sulfate, the 25 mL round bottom was attached to the apparatus, and 5 mL of Br2/HBr mixture was obtained and placed in the round bottom. The reaction took place for 20 minutes. An orange liquid was obtained and placed in a 125 mL Erlenmeyer flask along with 25 mL of water and 2.5 mL of conc. Sodium bisulfate soln. The solution was then placed in an ice bath to precipitate and then the solid product was filter in a Buchner funnel. These crystals were then re-dissolved minimum amount of hot solvent (heptane) and recrystallized. Once a dry product was obtained, a melting point was established (2,4-Dibromoanisol mp 55-58 C) and percent yield was established (52%).
As a result, the laboratory experiment was determined to be successful and the two product samples obtained and completed calculations displayed that overall bromide was a stronger nucleophile as the chloride ion was more electronegative than bromide, which allowed it to hold electrons in closerE. In conclusion, since bromide is less electronegative and has more electrons, it was able to share the unpaired electrons more easily than chlorideA. These results were expected, as the alkyl bromide would be the major product of procedure A as it followed the SN2 mechanism which was based on nucleophile strength and the product from procedure B would be a near-equal mixture as it followed the SN1 reaction mechanismC. The methods used during this experiment allowed for a successful completion and determination of the better nucleophile, but other additions and observations would have been interesting and beneficial as well. A possible examination of the two sample products collected using pH tested values or observation of sample spotted chromatography paper under a
Investigating How the Concentration of Hydrochloric Acid Affects the Rate of Reaction with Calcium Carbonate
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The Effect of Concentration of Hydrochloric Acid on the Rate of Reaction with Magnesium Aim: To investigate the effect of concentration of hydrochloric acid on the rate of reaction with magnesium Prediction: As the concentration of the hydrochloric acid increases, so will the rate of reaction Hypothesis: In a reaction, particles of two different reactants react together to form a product. The reaction only takes place on account of two things, if the particles collide, and if the collision has enough 'activation energy'. The two reactant particles, in this case magnesium particles and hydrochloric acid particles, must collide with each other on the correct 'collision course'. If this does not occur then no chemical reaction will take place. The reaction must also have enough energy, this can be affected by temperature, the more heat the particles have the faster they move and so the more energy therefore more chance of successful collisions.
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