hokiegirl

Formic Acid, HFor, has a Ka value equal to about 1.8 x 10^-4. A student is asked to prepare a buffer having a pH of 3.90 form a solution of formic acid and a solution of sodium formate having the same molarity. How many milliliters of the NaFor solution should she add to 20. mL of the HFor solution to make the buffer?

Could someone please explain how to find the answer? I'm a little lost

Last April/May, I got a one month membership to my local tanning salon, but then I stopped going and didn't continue a membership there. If I went back now to start up a membership, would they just continue my old one from last year or would I likely just start over as a new member? I appreciate any help!

I really want to see my favorite band play a concert in my area. The only problem is I think the performance is going to be at a nightclub, and I'm not 18 yet. Will I probably be able to go see them or not?

I was running a few days ago in my basement (I know, bad idea, but it was too late to go out running and the treadmill wasn't working...). I ran laps around the room. Since there's furniture, I was also making sharp turns around the furniture, and I was also running really hard/fast because I was doing a workout. Now the outer side of the front of my right ankle is really hurting whenever I move it certain ways, especially when I'm standing and twist my leg at all.

My track coach told me to go see the trainer but I haven't been able to, and also don't want to go yet and find out I'm just making a big deal out of nothing. Should I go to see the trainer or a doctor, or should I just wait and hope it gets better soon?

By the way- It's been 4 days since this happened, and the pain hasn't gone away or gotten better yet.