Easy Acid-Base titration problem i think

[gotmilk954]

Easy Acid-Base titration problem... i think URGENT!

So i just got my final exam for chem 2 back and i missed an A by two question. The thing is these two questions i was for sure i got right but apparently i didnt... here they are:

Use the following information: 50 mL solution of 0.053M HCL is titrated with .080M KOH
(I assumed a strong acid strong base titration)

First question:
How many ml KOH are needed to reach the equivalence point?
I put 33.1 mL which was wrong

Second question:
What would be the pH at the equivalence point?
I put 7 which was wrong

Any help?

 

[Nemus]

No help, I get the same answers. Odd.

 

[Borek]

33.1mL looks OK, final pH of 7 looks OK as well.

I can see a reason why final pH should be 6.98 or 6.99, but I doubt you were expected to dig that deep.

 

[kotreny]

Third to attest the correctness of your answers. You deserve an A, so something's up.

 

[LudusRex]

Hello there,

I understand your frustration with missing an A by just two questions on your final exam. Let's take a look at the questions and see if we can figure out what went wrong.

For the first question, you correctly identified that this is a titration between a strong acid (HCl) and a strong base (KOH). We can use the formula M1V1 = M2V2 to solve for the volume of KOH needed to reach the equivalence point.

M1 is the initial concentration of the acid (0.053M) and V1 is the initial volume (50mL). M2 is the concentration of the base (0.080M) and V2 is the volume of base needed to reach the equivalence point, which is what we are trying to find.

Plugging in the values, we get (0.053M)(50mL) = (0.080M)(V2). Solving for V2, we get V2 = 33.125mL, which rounds to 33.1mL. So it looks like your calculation was correct, but perhaps there was a rounding error or a typo in your answer.

For the second question, the pH at the equivalence point of a strong acid-strong base titration is indeed 7. This is because at the equivalence point, the moles of acid and base are equal, resulting in a neutral solution with a pH of 7. It's possible that there was a mistake in the question or in the answer key.

In any case, I would suggest talking to your professor about these questions and showing them your work. They may be able to provide some clarification or potentially even give you credit for the questions if there was an error on their end.

I hope this helps and good luck with your future chemistry studies!