Hi Steve and all! A couple of questions. Thanx in advanced!
You don't have to solve the problems if you don't wish you, but more importantly can you explain what's happening and how to approach the problem..
1) What is the pH of a solution obtained mixing 200ml of 0.4 M aq ammonia (NH3) with 300ml of 0.2 M HCl? (Kb = 1.8 E-5)
2)What is the pH of a solution obtained by mixing 400ml of 0.2M NaOH with 150ml of 0.1 m H3PO4 (phosphoric acid)?
(pKa's are 2.12, 7.21, 12.32
In this problem there are a couple of things I don't understand. First, I notice that the number of moles of NaOH are almost 8 times more than that of the weak acid itself. Does this mean that the only necessary pKa is the last one since the final pH will be close to the 3rd pKa?
And this brings another question, when dealing with polyprotic acids, how do I know which Ka I should be using? |
Free Forum Hosting
Important Announcement
Prev Message
