Kinetics of De-Esterification for Synthesis of Benzoic Acid Essay
The sodium hydroxide solution was created by dissolving its pellet-form in ODL water. The ethanol content would be varied in every trial. Concentrations that were used in the reactor were 25 mol % and 35 mol % of ethanol.
During the reaction, 10 ml samples were taken on a 10 minute interval over the course of an hour to compare the differences in benzene acid concentration. This Mould allow for the determination of the rate constant by noting the change in acid concentration. Water is used to clean the reactor after the reactor is drained of the previous mixture.
The samples were quenched with 10 ml of hydrochloric acid which Mould stop the reaction. These samples were refrigerated which prevented the reaction from progressing any further.
Once the Tiresomeness was available, all of the samples were taken to it to analyze the concentration of benzene acid in the solution. Adding water to the sample would not affect data taken from the retrospectives. The samples were often too low in volume for the titrating equipment to be able to take a reading, so approximately 50 ml of denizen water was added to each sample so that the sample could be titrated.
A titration involves using a controlled reaction between a solution of known concentration and a solution of unknown concentration to determine the concentration of the unknown solution. In this case, Noah is slowly added to our benzene acid solution by the Tiresomeness. At the same .
4- added vs… PH.
At this point we can find the concentration of our acid solution by knowing the concentration and volume of Noah added and the volume of our solution tested. This result will be printed by the Tiresomeness. Cave = C.v.
SAFETY This experiment involves the use of several hazardous compounds: ethanol lambed), ethyl abnegate (toxic), sodium hydroxide (toxic), and hydrochloric acid toxic). To prevent exposure, follow these guidelines: 1. Never work in the lab without supervision from a TA. 2.
Always wear PEE I. E. Gloves and goggles. 3. Be aware of all suspicious activity, if unsure of something, ask the TA. 4.
Always Near proper clothing I. E. Pants, closed-toed shoes, hair tied back. 5. No eating, drinking, or smoking in the lab. 5.
DATA COLLECTION rhea data collected made sure that there are only 2 varying parameters – Ethanol concentration in the reactant solution and Temperature of reactor. The stirrer speed Nas not chosen to vary because of a similar experiment by Peace et. Al, who found out that using FIT analysis that there is no practical difference in Ethyl Abnegate and Sodium abnegate concentration profiles regarding the rotational frequency of the stirrer Figure 5. 1 – Lamentation of Rate law data vs..
. Time at 25% OTOH concentrations at constant T Figure 4. 2 – Lamentation of Rate law data vs… Time at 35% OTOH concentrations at 30th figures 4.
And 4. 2 show how as Temperature increases, the rate constant also Increases provided that the Ethanol concentration stays constant. This is true for both 25% and 35% OTOH by volume. Moreover, reaction at higher temperature has a higher variance, meaning the experimental stays close to the expected. This was not seen in the 35% OTOH due to several sources of error involving the Tiresomeness.
Figure 5. 3 – Benzene Acid concentration curves at various OTOH mole fractions and temperatures 6. RESULTS parameters and the Awareness constants that represent the alkaline hydrolysis reaction of ethyl abnegate.
The rate constant, k, is determined by varying the reactor temperature and mole fraction of OTOH in reactant solution, which is then put wrought a volumetric analysis (titration) to measure the final concentration of ethyl abnegate.
The data are plotted in figures 5. 1 and 5. 2. The slopes of the plots represent the value of the rate constants at a set temperature. This is because the concentration vs.
.. Time data fit a linear model, and based on the rate law derived in section 2. 2.
Therefore, a positive slope can be expected for this model and was seen. From figure 5. , the Benzene Acid concentration should increase as the reaction time increases. This is because the reaction is a reversible, which means there is a rate determining step found at the point of equilibrium.
An overnight sample that was titrated found results of 0. 0911 of the 0. MM concentration. Here in this fugue, the dotted lines represent ICC and solid lines represent 45 co. For a constant temperature, a lower OTOH mole fraction yields a higher Benzene acid concentration.
This is true for both temperatures. However, the first experiment of the 25% OTOH Nas a not successful since it has several sources of error.
In order to verify the rate constants are correlated to the Benzene acid concentration, the Awareness constants re determined by varying the controlled variables, and verifying it with fugue 3 . Figure 6.
1 – Rate constant, k as a function of reactor temperature Table 6. 1 – Awareness constants k (L mol-l s-l) Ketch 15433 125 12012 135 16857 45 14976 40 (x IOWA L/mol*s) 10001 7. DISCUSSION rhea primary goal of this experiment was to determine the order of reaction for the reactants, ethyl abnegate and sodium hydroxide. As explained in section 2.
, since an equiangular amounts of reactants were added, the consumption rate of Ethyl Abnegate can be described by a simple second order kinetics. In the case-study with another e-stratification reaction of ethyl acetate to synthesize Acetic acid, a similar assumption was used, except it was a first order reaction due to one reactant dominating the other. Secondary goals of the experiment include the influence of reactor temperature on the rate constant, which then after analysis gives estimates for the pre-exponential factor AY and the activation energy, EAI for the benzene acid synthesis reaction.
The experiments were performed at different temperatures (40, 45 and ICC) with a constant stirring speed of 250 RPM. Due to a mechanical hardware problem, the ICC Arial was halted and the rate constant was calculated based on only two different temperature trials. Despite results correlating positively to literature values and past experiments, the ‘ales of the rate constants is skewed by a factor of 10 and product concentration of samples often fluctuate during consecutive iterations of titration.
Possible causes for these errors are listed as follows: 1 . Inaccurate thermocouple – The temperature readings on the Labeled software would fluctuate В± ICC. For temperatures tested – 40 and ICC, the first two samples – 10 and 20 min. Interval samples were “cloudy’ even after the quenching and cooling process, indicating that temperature control was a probable cause.
2. Improper use of Tiresomeness – the equipment required specific input strings and ‘ales and any incorrect coding on its keyboard may lead to a different value changed.
However, the machine had its own mechanical errors that it would not list the endpoint (the benzene acid concentration) on its printout of results, yet it lists the amount of Noah dispensed. In two calculations, the volume of the alkali solution dispensed for backtracking excess acid. 3.
Contamination of quenched solution during the titration process could have occurred in two ways: the pH probe was not cleansed with Ethanol since they are very sensitive or the Teflon (PETE) magnetic stir bar was not washed with ODL water for next use.
Since two lab experiment groups require the use of tiresomeness for data analysis, contamination could have very Nell happened. 4. Collecting samples from the reactor was difficult to retrieve exactly 10 ml of sample during the extracting process.
This could lead to inaccurate titration results Inch altered our reported concentrations. 5. Time constraints made it impossible to run multiple trials at the same conditions. Rhea heating of the batch on a set day would take up to 30-40 minutes and a 60 minute run of an experiment made carried a difficulty – especially with overall data emptying and cleaning each piece of equipment.
Comparison to Batch-based Bodiless synthesis: There are different branches that stratification has lead to in the past few decades, and these reactions model large scale industrial synthesis of Benzene acid and bodiless. Both of these products are based on De-stratification and transmogrification reactions. Knowing the kinetics of these syntheses help gain more understanding of upcoming chemical processes that may open new doors for the chemical engineering field, especially in renewable energy.