- #1
ducmod
- 86
- 0
Hello!
I am trying to crack the following problem:
What is the pH of a solution formed by mixing
125.0 mL of 0.0250 M HCl with 75.0 mL of 0.0500 M
NaOH?
Here is how I am approaching the issue:
both HCl and NaOH are strong acid and base respectively. Hence the concentration of [H3O+] = 0.003125M (this is the amount of moles of HCl in 0.125 L) and [OH-] = 0.00375M
Kw = [H30] x [OH] = 10^(-14)
the difference between [H30] and [OH] = 0.00375 - 0.003125 = 0.000625, which tells me that there are more [OH] in solution; hence it is a basic solution. -log(0.000625) = 3.204
But if I subtract 3.204 from 14 I will get 11.8, but the answer is 11.495
I can get 11.495 if 10(-14) / 0.003125 and take a log. But it can't be right because that would give me pOh not Ph.
I will be grateful for your help!
I am trying to crack the following problem:
What is the pH of a solution formed by mixing
125.0 mL of 0.0250 M HCl with 75.0 mL of 0.0500 M
NaOH?
Here is how I am approaching the issue:
both HCl and NaOH are strong acid and base respectively. Hence the concentration of [H3O+] = 0.003125M (this is the amount of moles of HCl in 0.125 L) and [OH-] = 0.00375M
Kw = [H30] x [OH] = 10^(-14)
the difference between [H30] and [OH] = 0.00375 - 0.003125 = 0.000625, which tells me that there are more [OH] in solution; hence it is a basic solution. -log(0.000625) = 3.204
But if I subtract 3.204 from 14 I will get 11.8, but the answer is 11.495
I can get 11.495 if 10(-14) / 0.003125 and take a log. But it can't be right because that would give me pOh not Ph.
I will be grateful for your help!