Sunday

December 21, 2014

December 21, 2014

Posted by **jhon** on Thursday, February 16, 2012 at 12:49am.

I think I first need to find the moles of NaOH. Then, by using the formula.

H2A + 2NaOH ----> Na2A + 2 H20

I am stuck from here. Do I find the equivalence point of each and add them?

- Chemistry -
**DrBob222**, Thursday, February 16, 2012 at 1:05amThe easy way to do this is

mL x N x millieq wt = grams.

You had 2.6g in 100 and took a 10 mL aliquot to titrate; therefore, the mass of the sample titrated was 0.26g

So 21.6 x 0.1 x mew = 0.26.

Solve for mew. Multiply by 1000 to find equivalent weight and multiply by 2 to find the formula mass. I am so sorry that texts/IUPAC and others have done away with normality. One step solved this problem. It would have taken half a page and multiple steps to do it the "new" way.

- Chemistry -
**Alex**, Wednesday, March 12, 2014 at 11:17pmThis topic's pretty old, but I figured it would be worth it to have the new way to solve the problem posted as well. If you're like me you're a young whippersnapper who's never even heard of normality.

It's actually not as hard as DrBob says.

Molarity = moles/liter, so convert your NaOH added to liters then plug everything in like so:

0.1 M = moles/0.0216 L

This will give you the moles of NaOH in the solution. From the balanced equation you know there are 2 moles NaOH per 1 mol of H2A, so dividing moles of NaOH by 2 will give you moles of H2A.

The formula weight is simply the grams of H2A in the solution (0.26g) divided by the moles of H2A you just calculated. Divide this answer by 2 to find the equivalent weight (because H2A has 2 equivalents, or H+ ions).

**Answer this Question**

**Related Questions**

College Chemistry - I need help with this question!! a sample of pure KHP ...

Chemistry - 1 g of acid was mixed with 120 ml of distilled water and the ...

chemistry - Suppose that 0.483 g of an unknown monoprotic weak acid, HA, is ...

Chemistry - .050 mole of weak acid (HA) is dissolved in enough water to make 1.0...

Chemistry-Dr Bob help!! - 0.100 M solution of a weak acid, HX, is known to be ...

Chemistry - 3) 0.3382 g of an unknown diprotic acid, when dissolved in water, ...

Chemistry - When we mix NaOH and H2SO4 we get the equation OH-(aq) + H+(aq) --&...

chemistry - 2- A 0.310 M solution of a weak acid, HX, has a pH of 2.53 a. Find ...

Chem 1A - A 15.00 g sample of an ionic compound NaA, where A- is the anion of a ...

NEED HELP WITH CHEMISTRY HW - Ascorbic acid (vitamin C) is a diprotic acid ...