Concept explainers
(a)
To determine: The equation that relates the equilibrium constant with the standard enthalpy and entropy changes.
(a)

Answer to Problem 1DE
Solution: The relation between equilibrium constant, standard enthalpy change and entropy change is given as,
ΔS∘R−ΔH∘RT=lnK
Explanation of Solution
The relation between the standard free energy change, standard entropy change and standard enthalpy change is given by the formula,
ΔG0=ΔH0−TΔS0 ...(1)
Where,
- ΔG0 is the standard free energy change.
- ΔH0 is the standard enthalpy change.
- T is the temperature.
- ΔS0 is the standard entropy change.
The relation between standard free energy change and the equilibrium constant is given by the formula,
ΔG0=−RTlnK ...(2)
Where,
- R is the gas constant.
- K is the equilibrium constant. Substitute the expression −RTlnK in equation (1) in place of ΔG0 .
−RTlnK=ΔH0−TΔS0
Simplify the above equation to calculate the relation between K, ΔH0 and ΔS0 .
lnK=ΔH0−TΔS0−RT=ΔS0R−ΔH0RT
The relation between equilibrium constant, standard enthalpy change and entropy change is given as,
ΔS∘R−ΔH∘RT=lnK
(b)
To determine: The way to draw the graph of K and T data to calculate the standard entropy and enthalpy changes for the given drug candidate and DNA binding interaction.
(b)

Answer to Problem 1DE
Solution: The graph of K versus 1T is used to calculate the entropy and enthalpy changes for the given process.
Explanation of Solution
The standard enthalpy and entropy changes by using K and T data is calculated by using the formula,
lnK=ΔS0R−ΔH0RT
Where,
- ΔG0 is the standard free energy change.
- ΔH0 is the standard enthalpy change.
- T is the temperature.
- ΔS0 is the standard entropy change.
- R is the gas constant.
- K is the equilibrium constant.
The above equation is modified to draw the graph of K and T data as the equation of line (y=mx+c) as given below.
lnK=ΔS0R−ΔH0R(1T)
Where,
- lnK is the variable on the y axis of the graph.
- 1T is the variable on the x axis of the graph.
- −ΔH0R is the slope of the graph.
- ΔS0R is the intercept on y axis.
The graph of K versus 1T is used to calculate the entropy and enthalpy changes for the given process.
(c)
To determine: The explanation and experiment for enthalpy change for the given blind reason being close to zero and the entropy change being large and positive.
(c)

Answer to Problem 1DE
Solution: The bond breaking in drug candidate and bond formation in binding reaction uses all the energy produced in the binding reaction which makes the enthalpy change of the reaction close to zero and the breaking of bonds increases vibrations in the system which increases randomness; thereby increase in entropy change observed. This is determined by using the calorimetric technique.
Explanation of Solution
The given reaction of drug candidate with its DNA target involves the breaking of ionic bonds and formation of hydrogen bonds and the dipole-dipole interactions. These two processes occur simultaneously in the binding reaction. Therefore, the exchange of energy also occur in the reaction medium. The energy released in the bond formation is utilized in the bond breaking which makes the overall enthalpy change of the equilibrium reaction zero.
The equilibrium of drug candidate and DNA target with drug-DNA complex involves the breaking of bonds which increases the vibration in the system and increase in randomness of molecules increases the entropy change of the system.
The experiment designed to determine the values of enthalpy and entropy changes is the calorimetric technique. By using this technique the data of equilibrium constant and temperature is observed for the given reaction. The value of enthalpy and entropy change is determined by the slope and intercept of the graph.
The increase in the vibrations due to bond breaking increases entropy change in the system; whereas, the enthalpy change of the bond breaking and bond formation counterbalance each other which leads to the zero enthalpy change of the reaction. The calorimetric method is used to determine the values of enthalpy and entropy change.
(d)
To determine: The explanation and experiment for the value of enthalpy change is large negative and entropy change is small positive for the DNA binding reaction.
(d)

Answer to Problem 1DE
Solution: The process of DNA binding involves the formation of bonds which leads to high enthalpy change and less entropy change of the reaction. The entropy change and enthalpy change of the reaction is tested by using the calorimetric technique.
Explanation of Solution
The binding of DNA involves formation of bonds which always results in the release of energy. Therefore, the enthalpy change of the DNA binding reaction is high. The entropy change of the reaction is less because the formation of bonds does not involve increased vibrations in the system. The bond breaking increases the vibrations in the system which increases the entropy change that is not involved in DNA binding reaction. Therefore, the entropy change of the DNA binding reaction is small.
The entropy change and enthalpy change for the DNA binding reaction is tested by calorimetric techniques. The temperature of the reaction at regular intervals of time is observed to calculate the enthalpy change of the reaction and the concentration of species is observed at regular intervals to calculate the equilibrium constant of the reaction from which the value of entropy change is calculated.
The process of DNA binding involves the formation of bonds which leads to high enthalpy change and less entropy change of the reaction. The entropy change and enthalpy change of the reaction is tested by using the calorimetric technique.
Want to see more full solutions like this?
Chapter 19 Solutions
CHEMISTRY THE CENTRAL SCIENCE >EBOOK<
- The rate coefficient of the gas-phase reaction 2 NO2 + O3 → N2O5 + O2 is 2.0x104 mol–1 dm3 s–1 at 300 K. Indicate whether the order of the reaction is 0, 1, or 2.arrow_forward8. Draw all the resonance forms for each of the following molecules or ions, and indicate the major contributor in each case, or if they are equivalent. (4.5 pts) (a) PH2 سمةarrow_forward3. Assign absolute configuration (Rors) to each chirality center. a. H Nitz C. он b. 0 H-C. C H 7 C. ་-4 917-417 refs H 1つ ८ ડુ d. Но f. -2- 01 Ho -OH 2HNarrow_forward
- How many signals do you expect in the H NMR spectrum for this molecule? Br Br Write the answer below. Also, in each of the drawing areas below is a copy of the molecule, with Hs shown. In each copy, one of the H atoms is colored red. Highlight in red all other H atoms that would contribute to the same signal as the H already highlighted red. Note for advanced students: In this question, any multiplet is counted as one signal. Number of signals in the 'H NMR spectrum. For the molecule in the top drawing area, highlight in red any other H atoms that will contribute to the same signal as the H atom already highlighted red. If no other H atoms will contribute, check the box at right. No additional Hs to color in top molecule For the molecule in the bottom drawing area, highlight in red any other H atoms that will contribute to the same signal as the H atom already highlighted red. If no other H atoms will contribute, check the box at right. No additional Hs to color in bottom moleculearrow_forwardIn the drawing area below, draw the major products of this organic reaction: 1. NaOH ? 2. CH3Br If there are no major products, because nothing much will happen to the reactant under these reaction conditions, check the box under the drawing area instead. No reaction. Click and drag to start drawing a structure. ☐ : A คarrow_forwardPredict the major products of the following organic reaction: NC Δ ? Some important Notes: • Draw the major product, or products, of the reaction in the drawing area below. • If there aren't any products, because no reaction will take place, check the box below the drawing area instead. • Be sure to draw bonds carefully to show important geometric relationships between substituents. Note: if your answer contains a complicated ring structure, you must use one of the molecular fragment stamps (available in the menu at right) to enter the ring structure. You can add any substituents using the pencil tool in the usual way. Click and drag to start drawing a structure. Х аarrow_forward
- Predict the major products of this organic reaction. Be sure you use dash and wedge bonds to show stereochemistry where it's important. + ☑ OH 1. TsCl, py .... 文 P 2. t-BuO K Click and drag to start drawing a structure.arrow_forwardConsider this organic reaction: ( Draw the major products of the reaction in the drawing area below. If there won't be any major products, because this reaction won't happen at a significant rate, check the box under the drawing area instead. Click and drag to start drawing a structure. Х : а ค 1arrow_forwardIn the drawing area below, draw the major products of this organic reaction: If there are no major products, because nothing much will happen to the reactant under these reaction conditions, check the box under the drawing area instead. 1. NaH 2. CH3Br ? Click and drag to start drawing a structure. No reaction. : ☐ Narrow_forward
- + Predict the major product of the following reaction. : ☐ + ☑ ค OH H₂SO4 Click and drag to start drawing a structure.arrow_forwardConsider this organic reaction: ... OH CI Draw the major products of the reaction in the drawing area below. If there won't be any major products, because this reaction won't happen at a significant rate, check the box under the drawing area instead. ☐ No Reaction. Click and drag to start drawing a structure. : аarrow_forwardConsider the following reactants: Br Would elimination take place at a significant rate between these reactants? Note for advanced students: by significant, we mean that the rate of elimination would be greater than the rate of competing substitution reactions. yes O no If you said elimination would take place, draw the major products in the upper drawing area. If you said elimination would take place, also draw the complete mechanism for one of the major products in the lower drawing area. If there is more than one major product, you may draw the mechanism that leads to any of them. Major Products:arrow_forward
- ChemistryChemistryISBN:9781305957404Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistryChemistryISBN:9781259911156Author:Raymond Chang Dr., Jason Overby ProfessorPublisher:McGraw-Hill EducationPrinciples of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning
- Organic ChemistryChemistryISBN:9780078021558Author:Janice Gorzynski Smith Dr.Publisher:McGraw-Hill EducationChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage LearningElementary Principles of Chemical Processes, Bind...ChemistryISBN:9781118431221Author:Richard M. Felder, Ronald W. Rousseau, Lisa G. BullardPublisher:WILEY





