Question

A hydrobromic acid (HBr) solution has a molar concentration of 0.0085 M. Calculate the [H3O+], [OH-] and pH of the solution. (Remember that Kw= 1.0 x 10-14 M2.)"

Answer 1

The [
`\(\text{H}_3\text{O}^+\)`] in the hydrobromic acid (HBr) solution with a molar concentration of 0.0085 M is 0.0085 M. Given the relationship in a neutral solution ([
`\(\text{H}_3\text{O}^+\)`][OH-] = Kw), and knowing that Kw is 1.0 x
`10^((-14) )`
`M^2`, the [
`\(\text{OH}^-\)`] is also 0.0085 M. The pH of the solution can be determined using the formula pH = -log[
`\(\text{H}_3\text{O}^+\)`], resulting in a pH of 2.07.

Step-by-step explanation:

In a hydrobromic acid (HBr) solution, the molar concentration of HBr is given as 0.0085 M. Since hydrobromic acid completely dissociates in water, the concentration of
`\(\text{H}_3\text{O}^+\)` ions is equal to the concentration of HBr, which is 0.0085 M. This represents the hydronium ion concentration in the solution.

In a neutral solution, the product of [
`\(\text{H}_3\text{O}^+\)`] and [
`\(\text{OH}^-\)`] is equal to Kw (1.0 x
`10^((-14) )`
`M^2`). Given that [
`\(\text{H}_3\text{O}^+\)`] is 0.0085 M, [
`\(\text{OH}^-\)`] is also 0.0085 M. This is a consequence of the self-ionization of water, and in this case, it indicates that the solution is neutral.

To find the pH of the solution, the formula pH = -log[
`\(\text{H}_3\text{O}^+\)`] is used. Substituting the value of [
`\(\text{H}_3\text{O}^+\)`] (0.0085 M) into the equation, the pH is calculated to be 2.07. This value indicates that the solution is acidic, as it falls below the neutral pH of 7.

Understanding these calculations is crucial in evaluating the acidity or basicity of a solution, providing valuable information for various scientific and industrial applications.