Chemistry Extended Essay Essay

To check into the set up of 2-bromo-2-methyl propane concentration and temperature of the system on the drift of chemical reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcoholthrough by Habib Iscandar HinnFriends Boys SchoolJune 22, 2007To investigate the heart and soul of 2-bromo-2-methyl propane concentration and temperature of the system on the aim of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcoholIntroductionThe major consent to of the solvolysis of t -butyl chloride in 70 % piss 30 % propanone is t-butyl alcohol, with a smooth amount of isobutylene being formed as a by productAnd this is with accordance of first order kinetic and suggests a two step chemical mechanism in which the gait 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 at one term to respect able-bodied by nucleophile (in this reference nucleophile is a inert molecule) the initial product is t-butyl carbonium ion.Note1 if the nucleophile is neutral the product volition be charged since the leaving group take ups roughly(prenominal) bonding negatrons away with itSo chemists have proposed to general types of mechanism1- Nucleophilic telephone exchange Sn1The ionization step in a Sn1 reaction is end early(a)mic and a great deal s light than the exothermic neutralization of carbonium ion by a nucleophile. And so the compute determining step being the unimolecular ionization of the t-butyl chloride equation 4, and as a result, the everywhereall 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 cleverness of the product is lower than the energy of the reactant the reaction is exothermic, and if the product have h igher energy than the reactant the reaction 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- propanone declaration is t-butyl alcohol.(Note4 electrophile an electron deficient atom, ion or molecule that as affinity for an electron pair, and go away 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 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 insert in the fast second step , so their relative molar concentrations preferably than their nucleiophilities argon the primary product determining factor, and by using nucleophilic reply like pissing, so its high concentration will assure that alcohols are the major product, and because pee system have a high dielectric invariable (e=81) so water molecule tend to orient them-selves in such a way as to decrease the electrostatic forces between ions. And an all-important(prenominal) factor is the salvations which refer to water molecules ability stabilize ions by encasing them in a sheath of weakly bonded resolvent molecules1- Anions are solvated by atomic depend 1 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 numeration of each transition country and intermediate in a total reaction, the over all rate of reaction 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 reasonable concentration of t-butyl chloride in ascendent)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 issue becomes increasingly virulent 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 influence amount of NaOH. An indication dye (bromo-phenol blue) will change color when the NaOH has been neutralized, and total of the reaction should begin at the mo.So according to kinetic measurements commit of reaction = K t butyl chloride Where K is the specific rate eternal in S -1 and t butyl chloride is the concentration of t-butyl chloride in M.Our kinetic measurement will front on the determination of the amount of HCl produced by the reaction, so by monitor the color change of the acid base indicator, we will determine the magazine 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 integrate 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 cartridge holder t = 0Rcl t is the molar concentration at magazine t = tTwo methods to approximate K1- since the equationKt = 2.303 Log Rcl 0Rcl tIs an equation of a straight hound (y=mx+b) with slope k. and block =0, a plot of 2.303 log Rcl 0 / Rcl t versus t should yield 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 surfaceing the value of K and quit it in the rate of reaction equation Rate = KRcl where the concentration of Rcl is cognise we can prognosticate the value of the rate of reaction and we will happen upon its effect on the solvolysis of t butyl chloride in 70% water 30 % acetone origin.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 disunite of all of the t butyl chloride 1molecules having energies equal to or greater than activating 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 incompatible temperature, we see that the total work out of t- butyl chloride molecules with sufficient kinetic energy to undergo reaction increases with increasing temperature and consequently, so does the reaction rate.Note7 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 ANot e8 Ea is the activation energy, a constant characteristic of the reactionWe can calculate the rate constant at some 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 solution.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. cognitive processPart A the effect of concentration 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 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 flaskfulfulfulfulful and gauge it 1.2- Prepare ascorbic acid ml of 0.1 M NaOH solutions (in water) and put it in an Erlenmeyer and notice it 2.3- Using a burette take 30 ml of the solution in flask 1 and put it in some other Erlenmeyer and chase it 3.4- By a graduated pipette take 3 ml of sodium hydrated oxide 0.1 M in an Erlenmeyer flask and say it 4.5- Using a graduated cylinder measure 67 ml of distilled water added to an Erlenmeyer flask 4.6- attention deficit hyperactivity disorder two drops of Bromo-phenol blue indicator to flask 4.A, a, II-1- Add quick the solution in Erlenmeyer fla sk 4 to solution in flask 3 and fail the preventative watch to count for time in seconds.2- Swirl the miscellanea and later on one or two seconds immediately pour the have solutions jeopardize 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 scrape changing to yellow, then we stop the stopwatch and disgrace the time.4- Repeat the procedure at least three multiplication 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 fashion 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- Us ing 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 salutary with ice and water, allowing the temperat ure of the 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 i t 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 induce 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 co lor 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 numberTemperatureTime of 10 % reaction just 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 organic 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 Che mistry, 1984