Question

At a certain temperature, the pHpH of a neutral solution is 7.45. What is the value of KwKwK_w at that temperature? Express your answer numerically using two significant figures. View Available Hint(s)

Answer 1

Answer:

The value of Kw is 1.26 * 10^-15

Explanation:

Step 1: Data given

The pH of the neutral solution = 7.45

pH = -log[H+]

Kw = [OH-][H+]

Step 2: Calculate [H+]

pH = 7.45

-log[H+] = 7.45

[H+] =  10^-7.45

[H+] = 3.55 * 10^-8 M

Step 3: Calculate [OH-]

Since pH and pOH are equal in our neutral solution so are [H+] = [OH-]

[OH-] = 3.55 * 10^-8 M

Step 4: Calculate Kw

Kw = [H]*[OH]

Kw = 3.55 * 10^-8 M * 3.55 * 10^-8 M

Kw = (3.55 * 10^-8)²

Kw = 1.26 * 10^-15

The value of Kw is 1.26 * 10^-15

Answer 2

Answer:

1.3 × 10⁻¹⁵

Explanation:

At a certain temperature, the pH of a neutral solution is 7.45. Then, we can calculate the concentration of H⁺.

pH = -log [H⁺]

[H⁺] = antilog -pH = antilog -7.45

[H⁺] = 3.55 × 10⁻⁸

By definition, in a neutral solution the concentration of H⁺ is equal to that of OH⁻.

Finally, we can calculate the ionic product of water (Kw).

Kw = [H⁺] × [OH⁻]

Kw = 3.55 × 10⁻⁸ × 3.55 × 10⁻⁸

Kw = 1.3 × 10⁻¹⁵