Weak Acids - Problem Walkthroughs - AP Chem Unit 8, Topic 3b

[@arafreshad]

Hi Mr. Krug, just wanted to clarify. When writing out the acid dissociation reactions is it necessary on the exam to write the states associated with each reactant/product, or leave them off as u have? Thank u!!

[@JeremyKrug]

States such as (aq), (l), etc. are optional on the AP exam. Most of us who are teachers leave them on for completeness, but you won't be marked off if you leave them off. Good question!

[@wearablechief5226]

Hello Mr. Krug. In problem 3, could you explain why the second dissociation reaction has a negative 2 charge for C6H6O6?

[@JeremyKrug]

Sure! Since the HC6H6O6 ion has a -1 charge, when it loses a proton, it loses another positive charge, making the resulting ion more negative. That's why the charge of C6H6O6 is -2.

[@wearablechief5226]

@@JeremyKrug Thanks!

[@dolphin601]

Hello there Mr. Krug, sorry for disturbing. I just wanted to ask for how in the second problem, only 34.3% of the acid dissociated yet the pH is 0.48. Isn't that the pH of a strong acid?

[@JeremyKrug]

It could be, but remember that a strong acid isn't determined by its pH, it's determined by its percent dissociation. If it's only 34.3% dissociated, then by definition, it has to be a weak acid. Strong acids, when dilute, can have a pH as high as 4 or 5, even approaching 7, but they're still 100% dissociated. Good question!

[@dolphin601]

@@JeremyKrug I understand now! Thank you do much Mr. Krug!