[Kurogashi]

1.31g of antacid is weighed and mixed with 75.00 mL of excess 0.17 M HCL. The excess acid required 27.20mL of 0.097 M NaOH for back titration. Calculate the neutralizing power of the acid in terms of mmol H+ per gram of antacid.

Thanks for any help whatsoever.

[sjb]

1.31g of antacid is weighed and mixed with 75.00 mL of excess 0.17 M HCL. The excess acid required 27.20mL of 0.097 M NaOH for back titration. Calculate the neutralizing power of the acid in terms of mmol H+ per gram of antacid.

Thanks for any help whatsoever.

How many moles of NaOH did you consume in the titration?

[Kurogashi]

Is that something I need to find with what's given? If so, sorry but can you walk me through. Because honestly, my guess right now for your question is 0.0272L x 0.097M = 2.63x10^-3 mol. I wouldn't know the stoichiometric ratios cause I don't even know how antacids work. :S

...but if whatever I said above makes no sense, the moles of NaOH consumed was not given. :S

[Borek]

my guess right now for your question is 0.0272L x 0.097M = 2.63x10^-3 mol

the moles of NaOH consumed was not given. :S

You have just calculated it, so it was given just not as a number of moles.

What was initial amount of acid?

How much acid was neutralized by NaOH? (you already know that, if you think you don't)

How much acid has been neutralized by antacid before NaOH was added?

Do you know how to divide?

[Kurogashi]

I'm guessing the initial is not 0.17M but instead it's the final?
So to find out how much acid has been neutralized, I have to.. work backwards.. which I don't know how.
Sorry, I am still really confused. Would I need to make a chemical equation to solve this, and use molar ratios? I don't get the concept of NaOH being added after antacids, especially cause I don't know the chemical formula of this antacid.

[DrCMS]

OK lets do this very simply in words.

You add a known weight of an antacid to an excess acid.   All the antacid reacts with some of the acid.

To the acid that is left over you add NaOH until it is all neutralised.

You have the details of the amount of NaOH used - calculate the moles of NaOH

You have the details of the amount of HCl used - calculate the moles of HCl

How do NaOH and HCl react? - calculate the moles of HCl that reacted with the antacid

Divide the mmoles of HCl that reacted with the antacid by the weight of the antacid used to answer the question.