How to Calculate Delta G and Keq for Chemistry Test?

In summary, the first question involves finding the ratio of AB to A at equilibrium, given the equilibrium constant and concentrations of free molecules. The answer is 0.05 : 1. The second question asks for the Delta G value for the forward reaction, given the gas constant, temperature, and equilibrium constant. The answer is -1.18 kcal/mol. The formula for Delta G is K= \frac{[x]}{[A-x][B-x]}, which can be found in the text.
  • #1
huan.conchito
44
0
I got these two questions i have no idea how to do (i have answers, but no soln's)
1. Given that the affinity constatn Keq for rxn A+B=AB is 5x10^6 and the concentration of free molecules at equillibrium are Afree = 1x10^-4 and B = 1x10^-8, what is the ration of AB to A at equillibrium

ans: 0.05 : 1

2. What is the Delta G for the forward reaction x <-> y.
Given
R = 1.98x10^-3 kcal/molK
T = 298K
K'eq = 7.5

(ans: -1.18kcal/mol)
 
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  • #2
Read this before posting :

https://www.physicsforums.com/showthread.php?t=4825
 
  • #3
Use [tex]K_{eq} = \frac{[AB]}{[A]} [/tex]
 
  • #4
Gokul43201 said:
Read this before posting :

https://www.physicsforums.com/showthread.php?t=4825
you don't understant.. its not my hw. just tell me the formula for delta g, that's all i need
 
  • #5
[tex]K= \frac{[x]}{[A-x][B-x]} [/tex]

You should be able to find such equations in the text by yourself, the're all listed explicitly.

...since it's urgent
 

1. What is the relationship between Delta G and Keq?

The relationship between Delta G and Keq is described by the equation: Delta G = -RT ln(Keq). This means that the change in free energy (Delta G) is directly proportional to the natural logarithm of the equilibrium constant (Keq) at a given temperature (T).

2. How do I solve for Delta G and Keq?

To solve for Delta G and Keq, you will need to know the standard free energy change (Delta G°) and the equilibrium constant (Keq) at the given temperature. You can then use the equation Delta G = Delta G° + RT ln(Keq) to solve for Delta G. The value of Keq can be determined by dividing the concentrations of the products by the concentrations of the reactants at equilibrium.

3. What units are used for Delta G and Keq?

Delta G is typically measured in kilojoules per mole (kJ/mol) while Keq is a dimensionless quantity. However, Keq can also be expressed in terms of concentration (M) or partial pressure (atm) depending on the reaction and the units of the equilibrium constant.

4. Can Delta G and Keq be negative?

Yes, both Delta G and Keq can be negative. A negative Delta G indicates a spontaneous reaction, meaning the reaction will proceed in the forward direction. A negative Keq indicates that the concentration of products is greater than the concentration of reactants at equilibrium.

5. How can I use Delta G and Keq to predict the direction of a reaction?

If Delta G is negative, the reaction is spontaneous and will proceed in the forward direction. If Delta G is positive, the reaction is non-spontaneous and will proceed in the reverse direction. Keq can also be used to predict the direction of a reaction. If Keq is greater than 1, the reaction favors the products and will proceed in the forward direction. If Keq is less than 1, the reaction favors the reactants and will proceed in the reverse direction.

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