The pH of a solution is 2.3. Using the ionic product constant for water, the value of [OH–] is
a) 3 x 10–5 mol/L
b) 2 x 10–12 mol/L
c) 1 x 10–10 mol/L
d) 2 x 10–15 mol/L
e) 5 x 10–3 mol/L
To find the hydroxide ion concentration, we can use the formula for calculating the pH of a solution:
pH = -log[H+]
From the pH given, we can calculate the concentration of H+ ions:
[H+] = 10^(-pH)
[H+] = 10^(-2.3)
[H+] = 5.01 x 10^(-3) mol/L
Since water is neutral, the concentration of hydroxide ions (OH-) will be equal to the concentration of hydrogen ions (H+). Thus, the concentration of OH- is also 5.01 x 10^(-3) mol/L.
The closest answer choice is e) 5 x 10^(-3) mol/L.
are you sure?
Apologies for the mistake in my previous response. Upon reevaluating the calculation, the correct concentration of hydroxide ions ([OH-]) can be determined using the ionic product constant for water:
Kw = [H+][OH-]
At 25 degrees Celsius, the value of Kw is 1.0 x 10^-14. Given that [H+] = 10^(-pH) = 10^(-2.3), we can rearrange the equation to solve for [OH-]:
[OH-] = Kw / [H+]
[OH-] = (1.0 x 10^-14) / (10^(-2.3))
[OH-] = (1.0 x 10^-14) / (10^(-2.3))
[OH-] = (1.0 x 10^(-14+2.3))
[OH-] = (1.0 x 10^(-11.7))
[OH-] = 1.0 x 10^(-11.7) mol/L
Therefore, the correct answer is c) 1 x 10^(-11) mol/L.
what is the correct answer?
Apologies for the confusion. The correct answer is c) 1 x 10^(-10) mol/L.
To find the value of [OH-], we need to use the relationship between pH and pOH. The pH and pOH are related by the equation:
pH + pOH = 14
Given that the pH of the solution is 2.3, we can substitute this value into the equation to find the pOH:
2.3 + pOH = 14
Now, we can solve for pOH:
pOH = 14 - 2.3
pOH = 11.7
Next, we can use the relationship between pOH and [OH-] to find the concentration of hydroxide ions, [OH-]. The relationship is given by:
pOH = -log[OH-]
To find the value of [OH-], we need to calculate the antilog of the pOH value:
[OH-] = 10^(-pOH)
[OH-] = 10^(-11.7)
Using a calculator, we find that 10^(-11.7) is approximately 1.995 x 10^(-12). Therefore, the value of [OH-] is approximately 2 x 10^(-12) mol/L.
Therefore, the correct answer is b) 2 x 10^(-12) mol/L.