Good (free) Chemistry Help Sites?

@Pigglies (9339)
United States
January 22, 2007 1:01am CST
I seem to be having a lot of trouble with chemistry lately. It's been a few years since I took the previous courses, and now I'm falling behind. Specifically, I need help in determining pH and titrations (weak acids, weak bases, strong bases, strong acids, etc.). Ugh! Anyone know of some good sites that would help? I'm having such a difficult time with the book that I've nearly given up on trying to read that. And the lectures are okay, but go so quickly I can't copy everything down, and what I copy from the board often gets copied incorrectly. If I could just see this online somewhere in a better format than the book, it would really help. Maybe you've run across a helpful chemistry site and can share.
1 response
• South Africa
22 Jan 07
I dont know any website to direct you to but i would offer lettle help as much as i know.pH of a solution of the number that indicates the degree of acidity ot basicity of a solution. It is the negative logarithm of hydrogen ion concentration. -pH = -log(H+). During titration, the base in the conical flask h(as a pH ranging from 7 to 14) and the acid in the burrette (has a pH ranging from 1-7 depending on the acidity ie whether it is a weak or strong acid).The acid will neutralise the base gradually untill the pH of the solution become nuetral it 7. At this stage in indicator i will change collour corresponding to the medium. If you ask a more specific question i will be glad to answer you more on the subject.
@Pigglies (9339)
• United States
22 Jan 07
I know some basics of pH, but here's a sample problem of something in the homework I don't understand (if you could help, I'd be very appreciative!): A 25.00 mL sample of 0.3146M lactic acid (C2H4OCOOH) requires 19.63 mL of a sodium hydroxide solution to reach the equivalence point. Ka for lactic acid = 8.4 x 10^-4 A) Write a balanced net-ionic equation for the titration reaction. B) Calculate the molarity of NaOH used in the titration. C) Calculate the pH of the titration mixture at the equivalence point.
1 person likes this
• South Africa
30 Jan 07
B. For this one use the formular. CaVb/CbVb = Na/Nb where Ca and Cb stands for the concentration and acid and bade respectively. Na and Nb stands for the number of moles of the acid and base in the balanced equation. Ca is given 25ml Na is given. The only unknown is Cb which the Molarity.
1 person likes this
@Pigglies (9339)
• United States
31 Jan 07
Thanks! Now if I can just figure out rate laws tonight and titrations for the quiz tomorrow, I'll be all set. :) I am wishing I was taking another class right now so bad. But chemistry is really the class that's holding me back, so I need to be taking this one. Next quarter, o-chem! How fun that sounds huh? ;)