Solution X has a pH of 9.4, and solution Y has a pH of 7.4.

a. What is the [H3O+] in the solution X?
Express your answer using one significant figure.

b. What is the [H3O+] in solution Y?
Express your answer using one significant figure.

see below

Explanation:

[H₃O⁺] = 10^-pH

a) Soln X with pH = 4.9 => [H₃O⁺] = 10⁻⁴°⁹ = 2.51 x 10⁻⁵M

b) Soln Y with pH = 7.4 => [H₃O⁺] = 10⁻⁷°⁴ = 3.98 x 10⁻⁸M

a.  [H30+] = 4 * 10^-10 M

b. [H3O+]= 4 * 10^-8 M

Explanation:

Step 1: Data given

pH of solution X = 9.4

pH of solution Y = 7.4

Step 2: Calculate [H3O+] of solution X

pH = -log [H+]

[H+] = [H30+]

pH = -log[H3O+]

9.4 = -log[H3O+]

10^-9.4 = 3.98*10*-10

[H30+] = 4 * 10^-10 M

To control we can calculate pH

-log[4 * 10^-10] = 9.4

Step 3: Calculate [H3O+] of solution Y

pH = -log [H+]

[H+] = [H30+]

pH = -log[H3O+]

7.4 = -log[H3O+]

10^-7.4 = 4*10*-8

[H30+] = 4 * 10^-8 M

To control we can calculate pH

-log[4 * 10^-8] = 74

a.  [H30+] = 4 * 10^-10 M

b. [H3O+]= 4 * 10^-8 M

pH = 9.4

Explanation:

With the given molarity of OH⁻ species we can calculate the pOH of the solution:

pOH = -log[OH⁻]

pOH = 2.6

Now we can use the pOH to calculate the pH of the solution, with the following formula:

pH = 14 - pOH

pH = 14 - 2.6

pH = 9.4

So a solution containing a OH⁻ concentration of 0.0025 M has a pH of 9.4.