Question

What kind of solutions is the result of a weak acid plus a weak base?
Will it be slightly basic?

Answer 1

Depends. If you have a weak acid plus its conjugate base, and you have substantial amounts of both, you have what's called a buffer. It can be weakly acidic or weakly basic, depending on the inherent strength of the acid and on the exact amounts of both.

Answer 2

hmmm, well perhaps you can help me figure this problem out then.
We were given the salt MgF2.
We then had to determine the parent acid and base.
Finally determine the type of solution (neutral, acid, base)
For the parent acid I found HF and for the parent base I got Mg(OH)2
I'm not sure if I got the acid and base wrong but from what I saw in the book, they're both weak and now I don't know what kind of a solution I have.

Answer 3

Sound reasoning. Mg(OH)2 is a strong base, not weak. It's not very soluble, but if it's in contact with an acidic solution, it will readily react. It's a common ingredient in over-the-counter antacids, either as a solid or a suspension (tiny particles of solid suspended in a liquid).

But I'm puzzled by what you mean by "what kind of solution you have now." If the MgF2 were formed from the reaction of HF and Mg(OH)2, you'd have to do something like mix aqueous HF solution (which is extremely corrosive and dangerous stuff, by the way) with a suspension of Mg(OH)2 in water. Probably MgF2 would form as little crystals and drop out of solution (MgF2 isn't very soluble either). At no point would you really have a solution in which both HF and Mg(OH)2 had significant contributions.

Answer 4

That's where I went wrong. I marked it as a weak base.
Okay so Mg(OH)2 is a strong base and HF is a weak acid therefore when mixed the solution would be slightly basic.
I meant that I wasn't sure if the solution was supposed to be acid, base, or neutral. Sorry for my poor wording.
Thankfully I'm not actually mixing anything. It was just a question on a worksheet and the only problem I couldn't figure out.