Posted by pH levels on Saturday, July 30, 2011 at 7:02pm.
What is the pH of an aqueous solution of 0.10 M NaHC(3)H(2)O(4)?
What I did:
NaHC(3)H(2)O(4) + H(2)O--><--
Na + H(2)C(3)H(3)O(4) + OH
H(2)C(3)H(3)O(4) is Malonic acid with a Ka value of 1.5*10^(-3)
initial-change-equilibrium (i.c.e) table results: (x^2)/(0.10-x)
[OH] = x
pOH = -log(x)
pH = 14-pOH
pH = 7.91
not sure what I did wrong.
- chemistry - DrBob222, Saturday, July 30, 2011 at 10:19pm
I don't believe 10.9 is the correct answer.
If this is malonic acid, then NaHmal is the half neutralized salt of H2Mal and as such behaves as an amphiprotic salt. For simplified solutions the pH is given by 1/2(pK1 + pK2). For solutions that may not meet the criteria for that equation, one may use
(H+) = sqrt[(k2*C + Kw)/(1+ term)] where
term = C/k1
I worked the problem both ways using 2.83 for pk1 and 5.69 for pK2 and obtained pH = 4.26 for both equations. For what it's worth, your math is right but this is not the simple hydrolysis of a base HC3H2O4^- which is the basis of your solution.
- chemistry - DrBob222, Sunday, July 31, 2011 at 1:25am
After thinking about this for 2-4 hours, are you sure this is malonic acid? Malonic acid is H2C3H2O4 and the salts would be NaHC3H2O4 and Na2C3H2O4.
- chemistry - pH levels, Sunday, July 31, 2011 at 2:18pm
I guess not; I thought it was, but I could be wrong. If it's not malonic what do you think it is?
Answer This Question
More Related Questions
- chemistry - Calculate the equilibrium constant for the weak acid, CH3CH2CO2H, if...
- Chemistry - considering the polarity of each compound and that of a solvent in ...
- Chemistry - Can u please give me a balanced eqn. for the reaction of Malonic ...
- chemistry - A reaction mixture is in a 5.4 L flask at 25 oC initially contains ...
- chemistry - What is the percent ionization of 0.025 M chlorous acid, HClO2 ...
- chem - Malonic acid and succinic acid each have two different pKa values. ...
- CHEMISTRY HELP!! - Formic acid (HCHO2) is a component of bee stings. It is a ...
- chemistry - (Dr. Bob222) - A student attempted to synthesize malonic acid which ...
- chemistry - Estimate the equilibrium constant for the weak acid HCO2H, if a 2.19...
- Chemistry - Estimate the equilibrium constant for the weak acid HCN, if a 4.68×...