Multiple Choice
A 850.0 mL sample of 0.20 M HF is titrated with 0.10 M NaOH. Determine the pH of the solution after the addition of 850.0 mL of NaOH. The Ka of HF is 6.8 x 10^-4.
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17. Acid and Base Equilibrium
Acids Introduction
Multiple Choice
Which of the following represents the correct equilibrium expression for the first dissociation of Malonic Acid (H2C3H2O4) in water?
A
Ka1 = [H2C3H2O4][H^+]/[HC3H2O4^-]
B
Ka1 = [HC3H2O4^-][H^+]/[H2C3H2O4]
C
Ka1 = [HC3H2O4^-]/[H2C3H2O4][H^+]
D
Ka1 = [H2C3H2O4]/[HC3H2O4^-][H^+]
Verified step by step guidance1
Understand the concept of acid dissociation: When an acid dissociates in water, it releases hydrogen ions (H^+) and forms its conjugate base. The equilibrium expression for this process is based on the concentrations of the products and reactants at equilibrium.
Identify the chemical species involved in the first dissociation of Malonic Acid (H2C3H2O4): The dissociation can be represented as H2C3H2O4 ⇌ HC3H2O4^- + H^+. Here, H2C3H2O4 is the acid, HC3H2O4^- is the conjugate base, and H^+ is the hydrogen ion.
Write the general form of the equilibrium expression for the dissociation: The equilibrium constant (Ka1) is expressed as the ratio of the product concentrations to the reactant concentration. For the dissociation of H2C3H2O4, it is Ka1 = [HC3H2O4^-][H^+]/[H2C3H2O4].
Compare the given options with the correct equilibrium expression: The correct expression should have the concentrations of the products (HC3H2O4^- and H^+) in the numerator and the concentration of the reactant (H2C3H2O4) in the denominator.
Select the correct option: Based on the comparison, the correct equilibrium expression for the first dissociation of Malonic Acid is Ka1 = [HC3H2O4^-][H^+]/[H2C3H2O4].
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