Chemistry Extended Essay Essay

To canvass the matter of 2-bromo-2-methyl propane concentration and temperature of the system on the regularize of answer of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol make by Habib Iscandar HinnFriends Boys SchoolJune 22, 2007To investigate the proceeds of 2-bromo-2-methyl propane concentration and temperature of the system on the position of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcoholIntroductionThe major everyplacelap of the solvolysis of t -butyl chloride in 70 % wet 30 % dimethyl ketone is t-butyl alcohol, with a keen amount of isobutylene being formed as a by productAnd this is with accordance of first order kinetic and suggests a two quantity apparatus in which the lay out determining step consists of the ionization of t-butyl chloride, and in this mechanism a carbonium ion is formed as inter- mediate and this bonds straightway to close-fitting by nucleophile (in this sheath nucleophile is a in incompatible(p) mole cule) the initial product is t-butyl carbonium ion.Note1 if the nucleophile is neutral the product ordain be charged since the leaving group pips both(prenominal) bonding negatrons away with itSo chemists have proposed to general types of mechanism1- Nucleophilic exchange Sn1The ionization step in a Sn1 reaction is end some othermic and a great deal s refuse than the exothermic neutralization of carbonium ion by a nucleophile. And so the station determining step being the unimolecular ionization of the t-butyl chloride par 4, and as a result, the overall rate of reaction is not affected by changes in the concentration or kinds of nucleophilic reagents present.Note2 the factor which determines the mechanisms employed is typically the nature of the substratum it self and not the particular nucleophileNote3 if the sum of the naught of the product is lower than the energy of the reactant the reaction is exothermic, and if the product have higher energy than the reactant the rea ction is endothermic.2- Elimination E1 (elimination unimolecular)And because t-butyl chloride acts as a Lewis acid (an electrophile) and combines with a nucleophile to give a substitution product, so the major product of the solvolysis of t-butyl chloride in piss supply supply-dimethyl ketone resolve is t-butyl alcohol.(Note4 electrophile an electron deficient atom, ion or molecule that as affinity for an electron pair, and leave behind bond to a base or nucleophile.)(Note5 nucleophile and atom, ion , or molecule that has an electron pair that may be donated in forming covalent bond to an electerophile.)Evaluating the mechanismThe only reactant that is undergoing change in the rate determining step is t-butyl chloride and so such(prenominal) reactions is a unimolecular and follow a first order equation (Sn1, E1). This means that the rate of the reaction varies directly with the concentration of t- butyl chloride. And since nucleophilic only move into in the fast second step, so their relative molar concentrations quite a than their nucleiophilities be the primary product determining factor, and by using nucleophilic issue like irrigate, so its high concentration will assure that alcohols are the major product, and because water have a high dielectric eonian (e=81) so water molecule tend to orient them-selves in such a way as to decrease the electrostatic forces between ions. And an meaning(a) factor is the salvations which refer to water molecules ability stabilize ions by encasing them in a sheath of weakly bonded declaration molecules1- Anions are solvated by hydrogen bonding,2- Cations are solvated by nucleophilic sites on water molecule (oxygen). And in this case of t-butyl carbonium ion the nucleophiles form strong covalent bond to carbon and converting the intermediate to a substitution product.The reaction mechanism is a sequential ac take care of each transition pronounce and intermediate in a total reaction, the over all rate of reac tion is determined by the transition state of highest energy in the sequence, so the rate determining step is the rate determining step for both the Sn1 and E1 for t butyl chloride.(Note 6 the water soluble organic solvent acetone is used to keep a reason equal to(p) concentration of t-butyl chloride in ancestor)The balance equation for t-butyl chloride solvolysis in water-acetone solvent isThe effect of concentration on the solvolysis of t-butyl chloride in 70 %water 30 %acetone solvent.As the reaction proceeds the upshot becomes increasingly sulfurous until all of the t -butyl chloride has reacted and all HCl that can form has formed. So we will monitor the reaction by allowing HCl formed to neutralize a mold amount of NaOH. An indicant dye (bromo-phenol blue) will change color when the NaOH has been neutralized, and quantify of the reaction should begin at the arcsecond.So according to kinetic touchstonements yard of reaction = K t butyl chlorideWhere K is the specific rate uninterrupted in S -1 and t butyl chloride is the concentration of t-butyl chloride in M.Our kinetic measurement will wager on the determination of the amount of HCl produced by the reaction, so by supervise the color change of the acid base indicator, we will determine the cadence required for 10% of t-butyl chloride to hydrolyze by having 10 % as practically NaOH present as T-butyl chloride.Rate = d Rcldt Where Rcl =-dt Rcl = K RcldtRearranging,d Rcl = -K dtRclAnd incorporate for t=0 to t=t will give=Ln Rcl t Ln Rcl 0 = Kt 2.303 Log Rcl 0 = KtRcl t2.303 Log Rcl 0 = KtRcl tWhere Rcl 0 is the molar concentration at while t = 0Rcl t is the molar concentration at date t = tTwo methods to rate K1- since the equationKt = 2.303 Log Rcl 0Rcl tIs an equation of a straight banknote (y=mx+b) with slope k. and finish =0, a plot of 2.303 log Rcl 0 / Rcl t versus t should gestate a straight line with slope k.2- if the solvolysis reaction run to 10% completionThen,Rcl = 0 .90 Rcl 0Kt = 2.303 Log Rcl 0 = 2.303 log (1.11)0.90 Rcl 0And therefore,K = 0.104TSo by pass offing the value of K and countervail it in the rate of reaction equation Rate = KRcl where the concentration of Rcl is cognise we can opine the value of the rate of reaction and we will assist its effect on the solvolysis of t butyl chloride in 70% water 30 % acetone root word.The effect of temperature on the solvolysis of t -butyl chloride in 70%water 30%acetone solvent.In nearly every antecedent an increase in temperature causes an increase in the rate of reaction, because the total member of all of the t butyl chloride 1molecules having energies equal to or greater than activation energy (Ea)Corresponds to the shaded portion of the area under the curve increases by increasing the temperature and by comparing the area for two different temperature, we see that the total fraction of t- butyl chloride molecules with sufficient kinetic energy to undergo reaction increases with increasing temperature and consequently, so does the reaction rate.Note7 ever-changing the concentration affects the rate of reaction changing the temperature affects the rate constant as well as the rate.By finding the value of reaction rate constant K for different concentration of t-butyl chloride and different reaction temperature, we will find the effect of temperature on the solvolysis of t-butyl chloride in water acetone solvent.Quantitatively, K (s-1) is related to Ea and T by the equationK1 = Ae-Ea/RT1 1Ea is the activation energy, in joule / mole. (Jmol-1)A is a proportionality constant, in s-1R is the gas constant = 8.314 Jmol-1K-1e is the base of the natural logarithms.T is temperature in Kelvin.This relation ship is known as Arrhenius equationWe measure Ea by taking the natural logarithm of eq.1Ln K = ln A EaRTThus, a plot of ln k versus 1/T gives a straight line whose slope is equal to -Ea/R and whose intercept with coordinate is ln ANote8 Ea is the activation energy, a constant characteristic of the reactionWe can calculate the rate constant at some(prenominal) specific temperature if Ea and K at some other temperature are known.For any temp. T1 (known), Ea (known), K1 (known)K1 = A e -Ea/RT1For any other T2 (known) (K2 unknown)K2 = A e -Ea/RT2By dividing K1 over K2K1 = A e -Ea/RT1K2 A e -Ea/RT2Taking natural logarithm of both sides, we getLn K1 = Ea (1/T2 1/T1).K2 ROr in common logarithms (base 10 logarithms) givesLog K1 = Ea (1/T2 1/T1)K2 2.303 RAnd by finding the value of K2 we will be able to find the rate of reaction at T2 and we will find the effect of temperature on the rate of solvolysis of t butyl chloride in 70 % water 30 % acetone resultant role.By finding the values of reaction rate constant K for different concentration of t-butyl chloride and different reaction temperature, we will find the effect of concentration and temperature on the solvolysis of t-butyl chloride in water acetone solvent. mathematical functionPart A the effect of concentration on the rate of solvolysis of t butyl chloride in 70%water 30%acetone solvent.a-Experimental mathematical process to measure the cadence necessary for 10 % solvolysis of t butyl chloride (0.1 M concentration) in 70 % water 30% acetone solvent at get on temperature.A, a, I-1- Prepare 500 ml of 0.1 M t- butyl chloride in acetone only and put it in an Erlenmeyer flaskfulfulfulfulfulfulful and distinguish it 1.2- Prepare carbon ml of 0.1 M NaOH solutions (in water) and put it in an Erlenmeyer and adjudicate it 2.3- Using a burette take 30 ml of the solution in flask 1 and put it in some other Erlenmeyer and tick it 3.4- By a graduate pipette take 3 ml of sodium hydrated oxide 0.1 M in an Erlenmeyer flask and gauge it 4.5- Using a graduated cylinder measure 67 ml of distilled water added to an Erlenmeyer flask 4.6- extend two drops of Bromo-phenol blue indicator to flask 4.A, a, II-1- Add readily the solution in Erlenmeyer flask 4 to solution in flask 3 and beginning the head watch to count for time in seconds.2- Swirl the sort and after(prenominal) one or two seconds immediately pour the feature solutions acantha into Erlenmeyer flask 4 to minimize the errors in the results.3- The color of the mixed solutions is blue, so continue swirling the solution in Erlenmeyer flask 4 till the instant color of the solution belt down changing to yellow, then we stop the stopwatch and phonograph record the time.4- Repeat the procedure at least three quantify and calculate the average.5- Tabulate the results in record A.b-Experimental procedure to measure the time necessary for 10 % solvolysis of t butyl chloride (0.2 M concentration) in 70 % water 30% acetone solvent at board temperature.A, b, I-1- Prepare 500 ml of 0.2 M t- butyl chloride in acetone only and put it in an Erlenmeyer flask and label it 1.2- Prepare 100 ml of 0.1 M NaOH solutions (in water) and put it in an Erlenmeyer flask and label it 2.3- Using a burette take 30 ml of the solution in Erlenmeyer flask 1 and put it in another Erlenmeyer flask and label it 3.4- By a graduated pipette take 3 ml of sodium hydroxide 0.1 M in an Erlenmeyer flask and label it 4.5- Using a graduated cylinder measure 67 ml of distilled water added to an Erlenmeyer flask 4.6- Add two drops of bromo-phenol blue indicator to Erlenmeyer flask 4.A, b, II-1- Add quickly the solution in an Erlenmeyer flask 4 to solution in flask 3 and start the stop watch to count for time in seconds.2- Swirl the mixture and after one or two seconds immediately pour the combined solutions back into an Erlenmeyer flask 4 to minimize the errors in the results.3- The color of the mixed solutions is blue, so continue swirling the solution in Erlenmeyer flask 4 till the instant color of the solution start changing to yellow, then we stop the stopwatch and record the time.4- Repeat the procedure at least three times and calculate the average.5- Tabulate the results in record A.Part B the effect of temperature on the rate of solvolysis of t butyl chloride in 70%water 30%acetone solvent.a-Experimental procedure to measure the time necessary for 10 % solvolysis of t butyl chloride (0.1 M concentration) in 70 % water 30% acetone solvent at zero Celsius degree.B, a, I-1- Prepare 500 ml of 0.1 M t- butyl chloride in acetone only and put it in an Erlenmeyer flask and label it 1.2- Prepare 100 ml of 0.1 M NaOH solutions (in water) and put it in an Erlenmeyer flask and label it 2.3- Using a burette take 30 ml of the solution in Erlenmeyer flask 1and put it in an Erlenmeyer flask and label it 3.4- By a graduated pipette take 3 ml of sodium hydroxide 0.1 M in an Erlenmeyer flask and label it 4.5- Using a graduated cylinder measure 67 ml of distilled water added to Erlenmeyer flask 4.6- Add two drops of bromo-phenol blue indicator to Erlenmeyer flask 4.B, a, II-1- Suspend the Erlenmeyer flasks in a water bath all-embracing with ice and water, allowing the temperature of t he Erlenmeyer flasks and their contents to equilibrate for ten minutes.2- Adding quickly the solution in Erlenmeyer flask 4 to solution in Erlenmeyer flask 3 and start the stop watch to count for time in seconds.3- Swirl the mixture and after one or two seconds immediately pour the combined solutions back into Erlenmeyer flask 4 to minimize the errors in the results.4- The color of the solution after that will become blue, so continue swirling the solution in Erlenmeyer flask 4 till the instant color of the solution start changing to yellow we stop the stop watch and record the time5- Repeat the procedure at least three times and calculate the average.6- Tabulate the results in record B.b-Experimental procedure to measure the time necessary for 10 % solvolysis of t butyl chloride (0.1 M concentration) in 70 % water 30% acetone solvent at a temperature greater than room temperature by ten degrees.B, b, I-1- Prepare 500 ml of 0.1 M t- butyl chloride in acetone only and put it in an Erlenmeyer flask and label it 1.2- Prepare 100 ml of 0.1 M NaOH solutions (in water) and put it in an Erlenmeyer flask and label it 2.3- Using a burette take 30 ml of the solution in Erlenmeyer flask 1 and put it in an Erlenmeyer flask and label it 3.4- By a graduated pipette put 3 ml of sodium hydroxide 0.1 M in an Erlenmeyer flask and label it 4.5- Using a graduated cylinder measure 67 ml of distilled water added to Erlenmeyer flask 4.7- Add two drops of bromo-phenol blue indicator to flask 4.B, b, II-1- Suspend the flasks 3 and 4 in a water bath full with ice and water, allowing the temperature of the flasks and their contents to equilibrate for ten minutes.(to top the temperature of the water bath)2- Adding quickly the solution in flask 4 to solution in flask 3 and start the stop watch to count for time in seconds.3- Swirl the mixture and after one or two seconds immediately pour the combined solutions back into flask 4 to minimize the errors in the results.4- The color of the mixed solutions is blue, so continue swirling the solution in flask 4 till the instant color of the solution start changing to yellow we stop the stopwatch and record the time5- Repeat the procedure at least three times and calculate the average.6- Tabulate the results in record B.Record ARun reciteTemperatureTime of 10 % reaction median(a) time / secondsRecord BRun numberTemperatureTime required for 10% reactionAverage time/secondsAverage time/ secondsReferences* E. Brady, James. E. Humiston, Gerard., General Chemistry Principles and Structure, second edition, SI version, john Willy and sons, Inc.* Brewester, Vaderwerf and McEwen. Unitized Experiments in natural Chemistry, 3rd Ed.* Streitwieser, Andrew. H. Heathcock, Clayton. Introduction to Organic Chemistry.* H. Reusch, William. An Introduction to Organic Chemistry.* J. Laidler, Keith. Chemical kinetics. 2nd ed.* Search engines that where usedo www.google.como www.yahoo.com* Goldwhite, Harold. R. Spielman, John. College Chemist ry, 1984