Question

Determine the [ OH − ] , pH, and pOH of a solution with a [ H + ] of 8.2 × 10 − 10 M at 25 °C. [ OH − ] = 1.22 ×10 −5 M pH = 9.07 pOH = 4.91 Determine the [ H + ] , pH, and pOH of a solution with an [ OH − ] of 0.0073 M at 25 °C. [ H + ] = 1.37 ×10 −12 M pH = 11.86 pOH = 2.14 Determine the [ H + ] , [ OH − ] , and pOH of a solution with a pH of 7.20 at 25 °C. [ H + ] = M [ OH − ] = M pOH = 6.8 Determine the [ H + ] , [ OH − ] , and pH of a solution with a pOH of 6.43 at 25 °C.

Answer 1

Answer:

See explanation below

Explanation:

At the beggining of the  exercise, you already giving the solution for the 1st two problems, so I just going to answer the remaining question which are:

"Determine the [ H + ] , [ OH − ] , and pOH of a solution with a pH of 7.20 at 25 °C. [ H + ] = M [ OH − ] = M pOH = 6.8 Determine the [ H + ] , [ OH − ] , and pH of a solution with a pOH of 6.43 at 25 °C."

Now, to get every data in the problem, we need to write the expressions for every part, which are the following:

pH = -log[H⁺]   (1)

pH = 14 - pOH  (2)

[H⁺] = 10^(-pH)  (3)

[H⁺] = Kw / [OH⁻]   (4)

pOH = -log[OH⁻]  (5)

pOH = 14 - pH  (6)

[OH⁻] = 10^(-pOH)   (7)

[OH⁻] = Kw / [H⁺]  (8)

Now, according to the given data, we will use any of these eight expressions.

a) "Determine the [ H + ] , [ OH − ] , and pOH of a solution with a pH of 7.20"

We have pH, so in this case, we will use expression (3), (6) and (8):

[H⁺] = 10^(-7.20)

[H⁺] = 6.31x10⁻⁹ M

pOH = 14 - 7.2

pOH = 6.8

[OH⁻] = 1x10⁻¹⁴ / 6.31x10⁻⁹

[OH⁻] = 1.58x10⁻⁴ M

b) "The [ H + ] , [ OH − ] , and pH of a solution with a pOH of 6.43 "

In this case, we can use expressions (2), (4) and (7). Using those expressions we have:

pH = 14 - 6.43

pH = 7.57

[H⁺] = 10^(-7.57)

[H⁺] = 2.69x10⁻⁸ M

[OH⁻] = 1x10⁻¹⁴ / 2.69x10⁻⁸

[OH⁻] = 3.72x10⁻⁷ M