Chemistry Extended Essay Essay

To investigate the ensn atomic number 18 of 2-bromo-2-m ethyl group propane niggardness and temperature of the schema on the ordinate of answer of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcoholDone by Habib Iscandar Hinn wizs Boys trainJune 22, 2007To investigate the event of 2-bromo-2-methyl propane niggardness and temperature of the system on the roam in of chemical reception of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol introductionThe major result of the solvolysis of t -butyl chloride in 70 % peeing 30 % dimethyl ketone is t-butyl alcohol, with a sm each(prenominal) keep down of isobutylene be doed as a by harvest-feastAnd this is with accordance of first revision energizing and suggests a ii misuse machine in which the rate project blackguard consists of the ionization of t-butyl chloride, and in this mechanism a carbon paperium ion is organize as inter- center(a) and this bonds like a shot to near by nucleophile (in this issue nucleophile is a neutral molecule) the initial product is t-butyl carbonium ion.Note1 if the nucleophile is neutral the product leave behind be charged since the leaving group mobs twain bonding negatrons away with itSo chemists withdraw proposed to general types of mechanism1- Nucleophilic replacing Sn1The ionization step in a Sn1 chemical chemical answer is endothermic and oft slower than the strength-releasing neutralization of carbonium ion by a nucleophile. And so the rate find step beingness the unimolecular ionization of the t-butyl chloride equation 4, and as a result, the all(a) overall rate of reply is non affected by convinces in the slow-wittedness or kinds of nucleophilic reagents present.Note2 the factor which determines the mechanisms employed is typically the nature of the substrate it self and not the particular nucleophileNote3 if the sum of the energy of the product is lower than the energy of the reactant the response is exothermic , and if the product energize higher energy than the reactant the reception is endothermic.2- Elimination E1 (elimination unimolecular)And because t-butyl chloride acts as a Lewis sharp (an electrophile) and combines with a nucleophile to give a substitution product, so the major product of the solvolysis of t-butyl chloride in pee- propanone dissolver is t-butyl alcohol.(Note4 electrophile an electron deficient atom, ion or molecule that as affinity for an electron pair, and forget bond to a ascendent 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 solitary(prenominal) reactant that is allowing tilt in the rate ascertain step is t-butyl chloride and so such reactions is a unimolecular and follow a first mold equation (Sn1, E1). This means that the rate of the reaction varies directly with the concentration of t- butyl chloride. And sinc e nucleophilic lonesome(prenominal) move into in the fast second step, so their relative molar concentrations rather than their nucleiophilities be the primary product determining factor, and by using nucleophilic solvent like weewee, so its high concentration get out get word that alcohols are the major product, and because wet have a high dielectric immutable (e=81) so water molecule scat to orient them-selves in such a way as to decrease the static forces between ions. And an important factor is the salvations which stir to water molecules ability stabilize ions by encasing them in a sheath of lame bonded solvent molecules1- Anions are solvated by enthalpy 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 modal(a) to a substitution product.The reaction mechanism is a sequential distinguish of each transition state and in termediate in a total reaction, the over all rate of reaction is obstinate 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 propanone is utilize to keep a reasonable concentration of t-butyl chloride in outcome)The ease equation for t-butyl chloride solvolysis in water-dimethyl ketone solvent isThe publication of concentration on the solvolysis of t-butyl chloride in 70 %water 30 % propanone solvent.As the reaction proceeds the effect runs more and more acidic 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 predetermined amount of NaOH. An index dye (bromo-phenol blue) will change likeness when the NaOH has been neutralized, and clocking of the reaction should bewilder at the crying(a).So according to kinetic metermentsRate of reaction = K t butyl chlorideWhere K is the specific rate unremitting in S -1 and t butyl chloride is the concentration of t-butyl chloride in M.Our kinetic legal professionment will depend on the determination of the amount of HCl produced by the reaction, so by monitoring the saturation change of the acid base indicator, we will determine the eon required for 10% of t-butyl chloride to hydrolyze by having 10 % as much NaOH present as T-butyl chloride.Rate = d Rcldt Where Rcl =-dt Rcl = K RcldtRearranging,d Rcl = -K dtRclAnd integrating for t=0 to t=t will give=Ln Rcl t Ln Rcl 0 = Kt 2.303 pound Rcl 0 = KtRcl t2.303 lumberarithm Rcl 0 = KtRcl tWhere Rcl 0 is the molar concentration at duration t = 0Rcl t is the molar concentration at clock sequence t = t twain methods to place K1- since the equationKt = 2.303 Log Rcl 0Rcl tIs an equation of a true(a) line (y=mx+b) with position k. and intercept =0, a plot of 2.303 pound Rcl 0 / Rcl t versus t should gift a straight line with careen k.2- if the solvolysis reaction run to 10% utmostThen,Rcl = 0.90 Rcl 0Kt = 2.303 Log Rcl 0 = 2.303 log (1.11)0.90 Rcl 0And therefore,K = 0.104TSo by purpose the value of K and compensate it in the rate of reaction equation Rate = KRcl where the concentration of Rcl is cognize we can calculate the value of the rate of reaction and we will see its proceeds on the solvolysis of t butyl chloride in 70% water 30 % dimethyl ketone origin.The effect of temperature on the solvolysis of t -butyl chloride in 70%water 30% acetone solvent.In nearly every display case an increase in temperature causes an increase in the rate of reaction, because the total component of all of the t butyl chloride 1molecules having energies equal to or great than activating energy (Ea)Corresponds to the shaded portion of the athletic field under the curve increases by increase the temperature and by comparing the area for twain contrasting temperature, w e 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 incessant as well as the rate.By finding the values of reaction rate immutable K for several(predicate) 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 rest 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 know 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 specific temperature if Ea and K at some other temperature are known.For whatever 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 theme.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 concentrat ion and temperature on the solvolysis of t-butyl chloride in water acetone solvent. forcePart A the effect of concentration on the rate of solvolysis of t butyl chloride in 70%water 30%acetone solvent.a-data-based unconscious process to measure the succession necessity for 10 % solvolysis of t butyl chloride (0.1 M concentration) in 70 % water 30% acetone solvent at board temperature.A, a, I-1- determine 500 ml of 0.1 M t- butyl chloride in acetone notwithstanding and retch it in an Erlenmeyer flaskfulfulfulfulfulfulfulful and notice it 1.2- bring in 100 ml of 0.1 M NaOH settlements (in water) and redact it in an Erlenmeyer and approximate it 2.3- development a burette take 30 ml of the solution in flask 1 and put it in other Erlenmeyer and recording tag it 3.4- By a gradatory pipette take 3 ml of atomic number 11 hydroxide 0.1 M in an Erlenmeyer flask and label it 4.5- exploitation a graduated cylinder measure 67 ml of dis cashboxed water added to an Erl enmeyer flask 4.6- put up ii drops of Bromo-phenol blue indicator to flask 4.A, a, II-1- Add rapidly the solution in Erlenmeyer flask 4 to solution in flask 3 and become the go bad expect to total for time in seconds.2- spin the kind and aft(prenominal) one or two seconds at once pour the have solutions abide into Erlenmeyer flask 4 to calumniate the errors in the results.3- The deform of the mixed solutions is blue, so have-to doe with swirling the solution in Erlenmeyer flask 4 till the instant color of the solution jump out changing to yellow(a), then we stop the stop meet and eternalize the time.4- Repeat the cognitive process at to the lowest degree three multiplication and calculate the average.5- put off the results in learn A.b- experimental procedure to measure the time incumbent for 10 % solvolysis of t butyl chloride (0.2 M concentration) in 70 % water 30% acetone solvent at room 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- utilise a burette take 30 ml of the solution in Erlenmeyer flask 1 and put it in some other 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- exploitation 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 wampum the stop watch to count for time in seconds.2- Swirl the mixture and by and by 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 propagation 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- development 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 full with ice and water, allowing the temperature of the Erlenmeyer flasks and their limit to equilibrate for ex 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 chlor ide (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 circumscribe to equilibrate for ten minutes.(to reach the temperature of the water bath)2- Adding quickly the solution in flask 4 to solution in flask 3 and s tart 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. leger ARun numberTemperature time of 10 % reaction median(a) time / secondsRecord BRun numberTemperatureTime required for 10% reactionAverage time/secondsAverage time/ secondsReferences* E. Brady, James. E. Humiston, Gerard., ecumenical Chemistry Principles and Structure, second edition, SI version, antic Willy and sons, Inc.* Brewester, Vaderwerf and McEwen. Unitized Experiments in constituent(a) Chemistry, third Ed.* Streitwieser, Andrew. H. Heathcock, Clayton. Introduction to Organic Chem istry.* 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 Chemistry, 1984