Weak Acid - Strong Base titration. Too little information?

[stickynote]

Homework Statement

In order to achieve a high result in this chemistry assignment, I need to have demonstrated a knowledge of challenging content not discussed in class. Every other part of this assignment I've covered (Intro, method, discussion etc), I am just stuck with the calculations.

This is what I know:
Base: Sodium Hydroxide
Acid: Acetic Acid
Concentration of Base: 1.06M
pH of solution: 7
Volume of Base: 20mL
Volume of Acid: 26mL
pKa of Acid: 4.75

What I need to find out:
Concentration of Acid.

Homework Equations

Henderson Hasselbalch Equation ?
Not really sure what else is needed.

The Attempt at a Solution

Not even the slightest clue as to where to begin.

 

[QuarkCharmer]

If you say the content was not covered in class, then you may find this a useful resource. (Since you said you need to demonstrate a knowledge not simple "answer this one question"). This link has a series of short video lectures covering tritation and such.

http://www.khanacademy.org/?video=titration-roundup#chemistry

In the center column, you will see the Acid/Base lecture where it starts, but you might want to begin with the Buffers and Hendersen Hasselbalch video.

 

[stickynote]

Thank you that looks to be a great resource.

 

[Borek]

Looks to me just like a simple titration calculation:

http://www.titrations.info/titration-calculation