16.4 pH Calculations for Strong Acids and Bases | General Chemistry
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- Опубліковано 5 сер 2024
- Chad provides a comprehensive lesson on how to calculate the pH for solutions of Strong Acids or Strong Bases. As strong acids dissociate completely, calculating the H+ concentration is typically straightforward. From there you simply take the negative log to obtain the pH. Though H2SO4 is a polyprotic, strong acid, only the first H+ is strongly acidic and the small difference the second H+ makes is discussed. Finally, the unusual case of a very, very, VERY dilute solution of a strong acid is discussed and why the pH of such a solution is essentially still 7.
As strong bases dissociate completely calculating the OH- concentration is typically straightforward. As the Group 2 metal hydroxides have 2 OH- in the formula (for example Ba(OH)2) this must be accounted for as both hydroxide ions dissociate completely. From there you simply take the negative log to obtain the pOH and then subtract from 14 to obtain the pH. Finally, the unusual case of a very, very, VERY dilute solution of a strong base is discussed and why the pH of such a solution is essentially still 7.
I've embedded this playlist as a course on my website with all the lessons organized by chapter in a collapsible menu and much of the content from the study guide included on the page. Check this lesson out at www.chadsprep.com/chads-gener...
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00:00 Lesson Introduction
00:26 Calculating the pH of Strong Acids
03:38 pH of H2SO4 Solutions
05:56 pH of VERY Dilute Strong Acids
07:35 Calculating the pH of Strong Bases
08:50 pH of Ba(OH)2 Solutions
10:50 pH of VERY Dilute Strong Bases
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Just wanna say, ive been slacking hard this semester and my gen chem grades weren't looking so good. However, after finding your videos, nothing has been this helpful and you may have just saved my final, I appreciate it and you are a very talented and thorough teacher. Thank you.
You're welcome - glad the channel is helping.
Thank you for explaining this chapter so explicitly! A lot of teachers will just show the method and move on but you took your time to explain the concept.
Glad it helped - Happy Studying!
Thank you for these videos. It is obvious that you put a lot of thought and time into these. I am in general chemistry II and these videos are saving me because of how well you explain these concepts. Thanks!
Very welcome!
Thank you so much for these videos Chad! I am taking the DAT soon and you are such a life saver!
You're welcome, Son Pham - I hope you do well!
Thank you for these lessons!
You are very welcome Circuit Man! Very happy they are useful!
I do like the way you simplify things
Excellent!
Chad, I literally understood nothing my teacher said and after this video I understand it all!
Glad the video/channel is able to help you out!
Always like your videos👍
Great to hear it :)
First of all, thank you for these lessons they are helping me out tremendously, I had have a quick question though, for Ba(OH)2 you multiplied the concentration of .1 by 2 and got .2 but when you had H2 in H2SO4 you kept the concentration ,.1. the same. What am I missing?
Hi Yahya! In H2SO4, only the 1st H+ is strongly acidic and dissociates completely. I cover the difference between H2SO4 and Ba(OH)2 specifically as this is confusing in lesson 16.4: ua-cam.com/video/WUkiaeZe_3o/v-deo.html
I cover the H2SO4 right around 3:45 and Ba(OH)2 around 8:50. Hope this helps!
thanks king
You're welcome, V.H.!
When I do the -log(10^-10) for calculating the pH of a very dilute strong acid, I get pH = 10. So why does the pH still remain at 7?
Don't forget that pure water already has [H+]=10^-7M. This is usually ignored as it is much lower than the concentration of acid we add into water. But in the case of 10^-10M strong acid, it is actually the strong acid concentration that is significantly lower than 10^-7M and so we will ignore the contribution of the strong acid as insignificant. So the [H+] is still approximately 10^-7M and the pH is still close to 7. Hope this helps!
Nice sir,
Thanks again and glad you find these helpful!
@@ChadsPrep you are one of the grate person my rest of life. Because am become a scientist by you, love you lot sir.
I really do wish that your life is and will be full of good things. Best of wishes in your pursuit!
HCl having too low concentration got one of my friend's big exam :( thanks for explaining that
Most welcome.