A monoprotic weak acid when dissolved in water is 0.66% dissociated and produces a solution with a pH of 3.04. Calculate the Ka of the acid.

Question

A monoprotic weak acid when dissolved in water is 0.66% dissociated and produces a solution with a pH of 3.04. Calculate the Ka of the acid. g

in progress 0
Hưng Khoa 6 months 2021-07-26T12:26:08+00:00 1 Answers 24 views 0

Answers ( )

    0
    2021-07-26T12:27:35+00:00

    Answer:

    Ka = 6.02×10⁻⁶

    Explanation:

    The equilibrium that takes place is:

    • HA ⇄ H⁺ + A⁻
    • Ka = [H⁺][A⁻]/[HA]

    We calculate [H⁺] from the pH:

    • pH = -log[H⁺]
    • [H⁺] = 10^{-pH}
    • [H⁺] = 9.12×10⁻⁴ M

    Keep in mind that [H⁺]=[A⁻].

    As for [HA], we know the acid is 0.66% dissociated, in other words:

    • [HA] * 0.66/100 = [H⁺]

    We calculate [HA]:

    • [HA] = 0.138 M

    Finally we calculate the Ka:

    • Ka = \frac{[9.12x10^{-4}]*[9.12x10^{-4}]}{[0.138]} = 6.02×10⁻⁶

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )