Calculate the pH of each of the following solutions a) 3.3x10^-4 M Ba(OH)2
b) 5.5x10^-4 M HNO3

Question

Calculate the pH of each of the following solutions a) 3.3x10^-4 M Ba(OH)2
b) 5.5x10^-4 M HNO3

anonymous · Answer

@Photon336

photon336 · Answer

well for B it would be  pH = -log[H+] ~  -Log[5.5*10^-4]

photon336 · Answer

$$Ba(OH)_{2} --> Ba^{2+} + 2(OH^{-})$$

korosh23 · Answer

yes @Photon336 is right. Just to add some information. If the substance is an acid like HNO3 then you can easily do the -log and find PH. However, if it is a base. You have to find out the concentration of OH ion, but pay attention to BALANCING like above. The number concentration of OH- would varry. By doing - log of OH- you get POH which is NOT PH. You have to do this:

PKw = 14.00 (consider as infinite sig figs or decimal places)

PKw = PH + POH

PH = 14.00 - POH value

As you can see finding the PH for acid and bases is slightly different. 

Good luck!

anonymous · Answer

Thanks guys. I got it now. I thought I needed to do that but I was unsure about it so I wanted to double check.

korosh23 · Answer

Your welcome :)