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Chemistry

These values also imply that the reaction is pseudo first order reaction.
(iv) A plot of rate of reaction (J) vs. concentration of AsO33- i.e.[A] was made (figure 2, below). A linear trendline was drawn using MS excel. Slope of this plot gives the rate constant. The value of the rate constant is 5.3x10-3s.

d) From data given in table (2) a plot of lnkR' vs. 1/T was made (figure 3, below). Slope of this curve equals -E/R, where E is activation energy of the reaction and R is the Universal gas constant, which equals 8.38 Jmol-1K-1.
Therefore, -E/R = 8122.6 K
Or, E = 8122.6*8.38 Jmol-1= 68067.4 Jmol-168.7 k Jmol-1


Q3. a) The mechanism in this case is SN1 i.e. Nucleophilic Substitution of First Order. In this mechanism the carbonium ion forms first, to which the nucleofile OH- gets attached in no time. Because formation of carbocation is the slow or rate controlling step therefore this is a first order reaction. Therefore, rate of this reaction is proportional to concentration of hexan-3-ol. Because, carbocation is planer therefore, the nucleofile (OH-) has equal probability of attaching to it from both sides (above as well as below) of the plane. Thus, a mixture of both the optical isomers (R-isomer and S-isomer) forms in equal proportions. The mechanism is shown below:


b) (i) In this case S-isomer will form.
(ii) The mechanism in this case is SN2 i.e. Nucleophilic Substitution of Second Order. In this case both molecules R-3-bromohexane and NaOH are involved in the reaction mechanism. The nucleofile OH- attacks the positively polarized carbon atom from the other side of the leaving group i.e. from other side of the C-Br bond, because of steric hindrance. This backside attack by the nucleofile...
1/T was made (figure 3, below). Slope of this curve equals -E/R, where E is activation energy of the reaction and R is the Universal gas constant, which equals 8.38 Jmol-1K-1.
Q3. a) The mechanism in this case is SN1 i.e. Nucleophilic Substitution of First Order. In this mechanism the carbonium ion forms first, to which the nucleofile OH- gets attached in no time. Because formation of carbocation is the slow or rate controlling step therefore this is a first order reaction. Therefore, rate of this reaction is proportional to concentration of hexan-3-ol. Because, carbocation is planer therefore, the nucleofile (OH-) has equal probability of attaching to it from both sides (above as well as below) of the plane. Thus, a mixture of both the optical isomers (R-isomer and S-isomer) forms in equal proportions. The mechanism is shown below:
(ii) The mechanism in this case is SN2 i.e. Nucleophilic Substitution of Second Order. In this case both molecules R-3-bromohexane and NaOH are involved in the reaction mechanism. The nucleofile OH- attacks the positively polarized carbon atom from the other side of the leaving group i.e. from other side of the C-Br bond, because of steric hindrance. This backside attack by the nucleofile leads to inversion of the stereo configuration of the molecule. The reaction mechanism is shown below:
c) This is because, in the beginning, when the reaction is being carried out in pure water, the ...Show more

Summary

d) Value of is negative, besides, value of will be very small in magnitude, therefore, value of will be negative and its value will be vary close to -78 kJmol-1. Because, value of is negative, therefore, MgBr(s) would be expected to be stable with respect to the elements.
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Chemistry Lab Report essay example
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