posted by .

What mass of propanoic acid, CH3CH2COOH, pKa= 4.87, should be dissolved in water to 2.00L volume in order to produce a pH of 2.50?

THANKS!

-J

Let's call propionic acid HP, then it will ionize as
HP ==> H^+ + P^-

First convert pH = 2.50 to (H^+) by
pH = -log(H^+).
Then set up the expression for Ka.
Ka = (H^+)(P^-)/(HP).
You know (H^+) now from the pH calculation. You know (P^-) because it equals the same as (H^+). (HP) = y-(H^+).
Solve for y which = (HP).
Then M x molar mass propanoic acid = grams propanoic acid.
Post your work if you get stuck.

• Jude -

When you do the -log of 2.50 you get a negative number, so I am not really sure what you do with that, do you not use the pKa for anything?

## Similar Questions

What mass of propanoic acid, CH3CH2COOH, pKa= 4.87, should be dissolved in water to 2.00L volume in order to produce a pH of 2.50?
2. ### Chemistry

Complete the reaction: Methanol and propanoic acid are mixed. Okay, I got the two formulas: CH3OH + CH3CH2COOH ---> ?
3. ### chemistry - buffers

what mass of sodium acetate should be dissolved in 1.00L of acetic acid, 0.150M concentration, in order to produce a buffer with pH = 4.5?
4. ### chemistry

propanoic acid ch3ch2cooh is a weak acid which has a value for dissociation content of ka = 6.3 x 10^-6 calculate the pH of an aqueous solution of propanoic acid containing 37 g of propanoic acid per litre. i'm stumbled on this one.. …
5. ### Chemistry

A 50.0 mL sample of 0.23 M propanoic acid, CH3CH2COOH, a weak monoprotic acid, is titrated with 0.14 M KOH. Ka of CH3CH2COOH = 1.4 multiplied by 10-5. What is the pH at equivalence point?
6. ### Chemistry

An equilibrium mixture of propanoic acid, CH3CH2COOH and its conjugate base has a pH of 4.87. What form predominates after H3O+ is removed?
7. ### Chemistry

Need help with AP chemistry, specifically Acids and Bases The acid ionization constant, Ka, for propanoic acid, C2H5COOH, is 1.3  10 -5 . (a) Write the expression for the acid-dissociation constant, Ka for propanoic acid. (b) …
8. ### chemistry buffers

What molar ratio of HPO4 2- to H2PO4 - in solution would produce a pH of 7.0?
9. ### Bio Chem

The pKa of propanoic acid (propionic acid), CH3CH2COOH, is 4.87. Consider an equilibrium mixture of propanoic acid and its conjugate base with a pH of 4.87. Draw the structure of the form (acid or conjugate base) that predominates …
10. ### Chemistry

In lab, we were finding the distribution coefficient for propanoic acid and ethyl acetate. As well as propanoic acid and toluene. How would you write the chemical equation for the reaction of propanoic acid and ethyl acetate?

More Similar Questions