Chemistry Assignment: Equilibrium, Thermodynamics Solutions

This chemistry assignment solution covers key concepts in chemical equilibrium, thermodynamics, and electrochemistry. The document provides detailed solutions to several problems, including calculating equilibrium constants (Keq) and Gibbs free energy changes (∆G) for various reactions. The solutions demonstrate the application of relevant formulas and principles, such as the relationship between Keq and ∆G, and the calculation of overall equilibrium constants for coupled reactions. Furthermore, the assignment addresses the calculation of free energy under non-standard conditions and explores electrochemical concepts like voltage, dimensions of voltage, the SI unit of voltage, and Faraday's constant. The solutions are supported by clear explanations and references to relevant resources.

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Solutions
Question 1
a)
Keq = Concentration of product ∈ solutionat equilibrium
Concentration of reactant∈ solutionat equilibrium
Keq= [ product ]
[ reactant ]
Keq = [ 0.25 ]
[ 0.75 ] =0.33
∆ G0 =−RT ln (¿ K eq)¿
R=1.986 cal/mol . K
∆ G0 =−1.986∗cal/mol . K ( 273.15+ 25 ) K ln(¿ 0.33)¿
∆ G0 =656.467 cal/mol
∆ G0 =656.5 cal/mol
∆ G0 =0.656 5 k cal/mol
b)
Keq= [ product ]
[ reactant ]
Keq= [ 99.999 ]
[ 0.001 ]

Keq=1.0∗104
∆ G0 =−RT ln(¿ K eq)¿
∆ G0 =−1.986∗cal/ mol . K ( 273.15+ 25 ) K ln (¿ 1.0∗104 )¿
∆ G0 =−5453.68 cal/mol
∆ G0 =−5454 cal/mol
∆ G0 =−5 . 454 k cal /mol
Question 2
The mechanism isocitrate decomposition to glyoxylate and succinate can be written and
condensed to an equation below showing a reactant to products ratio of 1:1.
isocitrate
⇔
glyoxylate+succinate
Assuming that only x amount of isocitrate is broken down to glyoxylate and succinate,
the concentration of the formed products will be x.
The equilibrium constant will be given as:
Keq= [ product ]
[ reactant ]
Keq = [ glyoxylate ] [ succinate ]
[ isocitrate ]
[ isocitrate ]eq=1−x
[ succinate ] eq=x
[ glyoxylate ]eq=x
Keq =0.07= [ x ] [ x ]
[1−x ]
Solving the above as a quadratic equation:
0.07 ( 1−x ) =x2

0.07−0.07 x=x2
x2+0.07 x−0.07=0
x=−b ± √ b2−4 ac
2 a
x=−0.07 ± √ 0.072−4∗1∗−0.07
2∗1 =0.2319∨−0.3019
Therefore;
[ isocitrate ]eq=0.77 M
[ succinate ] eq=0.23 M
[ glyoxylate ] eq=0.23 M
Question 3
Since the overall reaction is a combination of two reactions taking place, the overall
equilibrium constant will be the product of the individual equilibrium constant of the
respective independent reactions.
glucose+ ATP ⇔
G−6−P+ ADP
G−6−P+H2 O
⇔
glucose+ P K1 eq=1.3∗102
The reverse of the equation (a) above takes place thus the equilibrium constant is the
inverse of he forward reaction as shown below;
glucose+P
⇔
G−6−P+ H2 O K1 eq
' = 1
1.3∗102
ATP+H2 O ⇔
ADP +P K 2 eq=1.3∗102
The overall equilibrium constant is
Keq .overall =K1 eq
' ∗K2 eq

Keq .overall= 1
1.3∗102 ∗1.3∗102=1
Question 4
The free energy change is calculated as
∆ G=∆ Go +RT ln (Keq)
Keq= [ product ]
[ reactant ]
Keq = [ 0.1 ]
[ 10−4 ]
Keq =103
Replacing the values of R, T and Keq into equation 1,
∆ G=−1510 cal
mol +1.986 cal
mol . K ∗( 273.15+30 ) K∗ln(103 )
∆ G=2648.85 cal/ mol
∆ G=2649 cal/mol
Converting calories to kilocalories
1 kcal=1000 cal
Thus;
2649 cal=2649 cal∗1kcal
1000 cal =2.649 kcal
∆ G=2.649 kcal/mol
Question 5
a. Electrostatic potential difference or voltage is a measure of the difference in
potential between two electrodes in a cell. It is the driving force of electrons
between two points in an electric circuit.

b. The dimensions of voltage are : M L2
q T 2
Where:
 q is the charge,
 M is the mass of the charge,
 T is time and
 L is the distance.
c. The SI unit of voltage is volts which is the energy in joules contained in a unit
charge particle or coulomb (Joules/Coulomb).
d. Faraday’s constant represents the amount of charge contained in one mole of
electrons.
e. the faraday’s constant is: F=96485.33289 C /mol

References
calistry.org. Standard Free Energy hange and Equilibrium Constant Calculator. Web. 31 March
2019<http://calistry.org/calculare/standard-Free-Energy-Change>
Clark, Jim. An Introduction To Chemical Equilibria. April 2013. Web. 31 April 2019. .<
http://www.chenguide.co.uk/physical/equilibria/introduction.html>