please help me figure this out----finding the pH of a solution of HCL and CH3COOH?

Question

What is the pH of a 1 liter solution containing 0.150 mole of CH3COOH and .100 mole of HCL?

I can do them if they have a salt and a weak acid mixed together, I tried to do it the same way with a strong acid and a weak acid, but it didnt come out right. I know the answer is a pH of about 4.57 but I cant find out what steps I need to go through to get it.

Answer 1

Between a strong acid and a weak base, you first have to compute the molarity of each.

Then you determine the amount of hydrogen ions each one contributes.

So given: 0.100 M HCl and 0.150 M CH3COOH.

Since HCl is the strong acid, it contributes 0.100 M of hydrogen ions into the solution. Since acetic acid is a weak acid, you have to go to the equilibrium equation of ionization.

So:
Ka = [H+][CH3COO-]/[CH3COOH]

So we know that [H+] would equal to the concentration of HCl. Now the contribution of H+ in the equilibrium would be equal to the concentration of [CH3COO-]
So:
[H+solution] = [CH3COO-] = Ka [CH3COOH]/[H+]
[H+solution] = 1.74 x 10 ^ -5 ( 0.150 M ) / (0.100 M )
[H+solution] = 2.61 x 10 ^ -4

Then, you can use this value to find the pH of the solution:
pH = - log [H+solution]
pH = - log 2.61 x 10 ^ -4
pH = 4.58

Answer 2

those are some fairly basic questions that could tell no count in case you recognize what acids and bases do. those are not as plenty "problems" as they're theoretical questions. a million. asks in case you recognize that HCl is an acid, and in case you recognize that acids neutralize bases...and can you establish which of those compounds ARE certainly bases. (i'm no longer telling you...) 2. do you recognize what a pH strengthen in fee (selection gets larger) skill in family to the hydronium ion concentration? What does pH going up advise in terms of acidity vs. basicity? And what foundation is the pH scale built on? 3. what's a buffer gadget...and what does including acid or base do to it? that's what those questions are asking you. Now crack your textbook open and locate out. those are no longer complicated problems...they're basic in nature. in case you're scuffling with them, i might advise which you accentuate or redirect a number of your attempt.

Answer 3

If you have a strong and a weak acid in the same solution then you can just ignore the weak acid (CH3COOH in this case) because it's dissociation is suppressed by the common ion (H3O+) effect. So, find the molarity of HCl:

C = n/V = 0.1/1 = 0.1 M

From the reaction:

HCl + H2O --> Cl- + H3O+

you get the [H3O+] = 0.1 M. And finally:

pH = -log[H3O+] = -log(0.1) = 1