Answer:
The fraction = 1/5
Step-by-step explanation:
a) Identify the acid, base, conjugate acid, and conjugate base in the given reaction.
The acid in the reaction is HClO (hypochlorous acid).
The base in the reaction is H2O (water).
The conjugate acid of the base is H3O+ (hydronium ion).
The conjugate base of the acid is Cl- (chloride ion).
b) Write the expression for the acid dissociation constant (Ka) for HClO in terms of the concentrations of its products and reactants.
The acid dissociation constant expression for the dissociation of HClO is:
Ka = [H3O+][ClO-] / [HClO]
c) Explain why HClO is considered a weak acid.
HClO is considered a weak acid because it only partially dissociates in water to form H3O+ and ClO-. This means that the concentration of HClO in solution is much greater than the concentrations of H3O+ and ClO-. Additionally, the acid dissociation constant (Ka) for HClO is relatively small, indicating that the dissociation reaction does not proceed to a large extent.
d) If the pH of a solution containing HClO and Cl- is 4.0, calculate the fraction of HClO in solution using the equation provided.
The pH of a solution containing HClO and Cl- is 4.0. This means that [H3O+] = 10^-4 M.
To calculate the fraction of HClO in solution, we need to determine the concentrations of HClO and Cl-. Since HClO is a weak acid, we can assume that the concentration of HClO in solution is equal to the initial concentration of HClO, and that the concentration of Cl- is equal to the initial concentration of Cl2.
Let x be the concentration of HClO in solution, then the concentration of Cl- is 2x (from the balanced equation).
The equilibrium expression for the dissociation of HClO is:
Ka = [H3O+][ClO-] / [HClO] = (10^-4)(2x) / x = 2 × 10^-4
Solving for x gives:
x = [HClO] = (10^-4) / 2 × 10^-4 = 0.5 M
Therefore, the fraction of HClO in solution is:
[HClO] / ([HClO] + [ClO-]) = 0.5 / (0.5 + 2(0.5)) = 0.2
The fraction of HClO in solution is 0.2.