If you had a solution of monosodium glutamate, which is glutamic acid's conjugate base with one sodium ion attached, in which only one of the two acid groups is deprotonated and attached to the sodium ion, would you expect such a solution to be acidic, basic, or neutral? Explain your reasoning.

Question

majikdusty · Answer

As far as I'm aware, both the base and two acids in glutamic acid are weak. I know when you have a weak acid and a weak base, it can go either way. How can I possibly know for sure what this is? I'm assuming it is neutral but i just don't know why.

photon336 · Answer

Conjugate acid base pair. 

two molecules that differ in the presence of a proton. 

HA/A-

photon336 · Answer

This is a good question. acidity/basicity stuff like that depends on how many H+ ions are in solution.

photon336 · Answer

@majikdusty there is something that we might be able to use to figure out it's called the pkA. we're not given the pH of the solution.

pKA = how well can a compound give up its proton. we know this we can probably infer wither it's acidic basic neutral stuff like that. 

$$kA = \frac{ [H][A^{-}] }{ [HA] }$$ 

$$ka > 0; [A^{-}] > [HA]; ka > 0 | [HA] > [A^{-}]$$

a large Ka means that there's going to be more conjugate base than the acid. well this means that the compound likes to really give up that proton really acidic.

if you notice. 

HA/A- 

the p just means -log(ka) 

pka is kind of a ratio of the concentration of the conjugate base to the acid. 

so I think you would probably look up the pKa for glutamatic acid  and then you could make the inference based on that.

photon336 · Answer

AND THEN, if you knew that if both groups are de-protinated then the solution is basic. because in a basic solution OH- predominates.

photon336 · Answer

ALSO, Draw out the compound that would result from losing one proton. and look at its structure, then infer what PH this would be that's another way.