Calculate the equilibrium constant for the weak acid, CH3CH2CO2H, if the aqueous solution of CH3CH2CO2H that has an initial concentration of 1.97E-2 M has a [H+] of 5.00E-4.
CH3CH2CO2H <=> CH3CH2CO2 + H
i know that to figure out the equilibrium constant it is kc = products/reactants
and i have to do something with the ICE table...but i don't know how to apply it...
Let's call CH3CH2COOH, just to save some time typing, HP.
HP ==> H+ + P^-
Ka = (H^+)(P^-)/(HP)
Initial concns:
(HP) = 1.97E-2
(H^+)= 0
(P^-) = 0
Equilibrium concns:
(H^+) = 5.00E-4
(P^-) = 5.00E-4
(HP) = 1.97E-2 - 5.00E-4
Plug those equilibrium values into the Ka expression and solve for K.
To determine the equilibrium constant (Kc) for the reaction, we need to first set up an ICE (Initial, Change, Equilibrium) table.
1. Write down the balanced equation for the reaction:
CH3CH2CO2H ⇌ CH3CH2CO2- + H+
2. Set up the ICE table:
CH3CH2CO2H ⇌ CH3CH2CO2- + H+
I (Initial) | 1.97E-2 M
C (Change) | -x +x
E (Equilibrium)| 1.97E-2 - x x x
3. The change in concentration for the weak acid (CH3CH2CO2H) is equal to the initial concentration minus the equilibrium concentration, which is x in this case.
During the reaction, the weak acid (CH3CH2CO2H) loses x moles, resulting in a decrease of concentration by x. The products, CH3CH2CO2- and H+, gain x moles and their concentrations increase by x.
4. From the given information, we know that the concentration of H+ is 5.00E-4 M at equilibrium. Therefore, we can write the equation:
[H+] = x = 5.00E-4 M
5. Now, substitute the equilibrium concentrations into the equilibrium expression:
Kc = ([CH3CH2CO2-] * [H+]) / [CH3CH2CO2H]
Since we know the concentration of [H+], we need to find the concentrations of [CH3CH2CO2-] and [CH3CH2CO2H].
Using the equilibrium concentrations from the ICE table:
[CH3CH2CO2-] = x = 5.00E-4 M
[CH3CH2CO2H] = 1.97E-2 - x = 1.97E-2 - 5.00E-4 = 1.92E-2 M
Substituting these values into the equilibrium expression:
Kc = (5.00E-4 M * 5.00E-4 M) / (1.92E-2 M)
Calculating this expression gives you the equilibrium constant (Kc) for the reaction.