Respuesta :

Answer:

Ka = 1.764 × 10^-4

Explanation:

The equation for the dissociation of methanoic acid which is a weak acid.

HCOOH + H2O  ⇄  H3O+ + HCO2-

But; [H3O+] = [H+] = 4.2 x 10-3M

Ka = [H3O+] [HCO2-]/ [HCOOH]

In this case;

[H3O+] = [HCO2-] = 4.2 x 10^-3M

[ HCOOH] = 0.100 M

Therefore;

Ka = [ 4.2 x 10^-3M] [4.2 x 10^-3M]/ [0.1000M]

    = 1.764 × 10^-4

dsdrajlin

A 0.1000M solution of methanoic acid, with an acid dissociation constant of 1.8 × 10⁻⁴, has a concentration of H⁺ of 4.2 × 10⁻³ M.

What is a weak acid?

A weak acid is an acid that partially breaks apart into its ions in an aqueous solution.

Let's consider the acid dissociation for methanoic acid.

HCOOH ⇄ HCOO⁻ + H⁺

In a 0.1000M solution of HCOOH, the concentration of H⁺ is 4.2 × 10⁻³ M. With this information, we can calculate the acid dissociation constant using the following expression.

Ka = [H⁺]² / Ca

Ka = (4.2 × 10⁻³)² / 0.1000 = 1.8 × 10⁻⁴

where,

  • Ka is the acid dissociation constant.
  • [H⁺] is the concentration of H⁺.
  • Ca is the concentration of the acid.

A 0.1000M solution of methanoic acid, with an acid dissociation constant of 1.8 × 10⁻⁴, has a concentration of H⁺ of 4.2 × 10⁻³ M.

Learn more about weak acids here: https://brainly.com/question/15192126

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