Calculating Equilibrium Concentrations - Chemistry LibreTexts

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Solution

Given: \(K_a\) for HC7H5O2= 6.4 x 10-5

Step 1: The ICE Table

HC7H5O2 H3O+ C7H5O2-
Initial Concentration 0.43 M 0 0
Change in Concentration -x +x +x
Equilibrium Concentration (0.43-x)M x M x M

Step 2: Create the \(K_a\) equation using this equation :\(K_a = \dfrac{[Products]}{[Reactants]}\)

\(K_a = \dfrac{[H_3O^+][C_7H_5O_2-]}{[HC_7H_5O_2]}\)

Step 3: Plug in the information we found in the ICE table

\(K_a = \dfrac{(x)(x)}{(0.43 - x)}\)

Step 4: Set the new equation equal to the given Ka

\(6.4 x 10^{-5} = \dfrac{(x)(x)}{(0.43 - x)}\)

Step 5: Solve for x.

x=0.0052

Tag » How To Find Equilibrium Concentration