Dat Destroyer Chem

[iphone2020]

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Hello everyone,
General chemistry question 31 version 2017.
I don't understand concept behind it. I know chad say something about it in his video but on paper it does not make sense.
Thanks


Sent from my iPhone using SDN mobile

 

[Zesta]

Perhaps post the question here and we might be able to help you.

 

[iphone2020]

Sorry I wish I could due to SDN policy you cannot post any question from destroyer. It is copy right so I cannot! I guess will have to wait and see! policies! lol every turn u take there is policy even when studying lol


Sent from my iPhone using SDN mobile

 

[DAT Destroyer]

Hello everyone,
General chemistry question 31 version 2017.
I don't understand concept behind it. I know chad say something about it in his video but on paper it does not make sense.
Thanks


Sent from my iPhone using SDN mobile

Normally, when we do simple pH calculations, we do NOT include the small amount of hydronium ions given by water. For example, in a 1x10-4 M solution of HCl, the amount contributed by water is so small, we neglect it. In this problem....it is tricky indeed........the amount of HCl was only 1x10 -12.......this is small....thus the hydronium ion contribution from water is NOW SIGNIFICANT !!!!!! Thus, the pH is essentially 7. Acid or base solutions that are at this very low concentration will essentially have a pH of 7. To prove this to yourself...if you add 1x10-12 + 1x10 -7.....you get 1x10 -7 !!!!

Hope this helps.

Dr. Romano

 

[iphone2020]

Understood, i though maybe because HCL is strong acid that is reason because it dissolve in water 100%. Maybe I am mixing concept.
Thanks


Sent from my iPhone using SDN mobile

 

[ppaa]

Normally, when we do simple pH calculations, we do NOT include the small amount of hydronium ions given by water. For example, in a 1x10-4 M solution of HCl, the amount contributed by water is so small, we neglect it. In this problem....it is tricky indeed........the amount of HCl was only 1x10 -12.......this is small....thus the hydronium ion contribution from water is NOW SIGNIFICANT !!!!!! Thus, the pH is essentially 7. Acid or base solutions that are at this very low concentration will essentially have a pH of 7. To prove this to yourself...if you add 1x10-12 + 1x10 -7.....you get 1x10 -7 !!!!

Hope this helps.

Dr. Romano

I was wondering at what starting amount of HCl would be considered dilute? 1x10^-10 and higher?

 

[DAT Destroyer]

I was wondering at what starting amount of HCl would be considered dilute? 1x10^-10 and higher?

Try to understand the concept. The amount of hydronium ion that you get from water alone is 1 x 10 exp -7,,,,,,,,thus anything like 10 exp-9, 10 exp-10, 10 exp-11 additional acid would indicate a VERY VERY dilute solution close to a pH of 7.

Hope this helps.

Dr. Romano