January 10, 2025, 03:10:35 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: 1 [2]   Go Down

Topic: how to figure out the concentration??  (Read 10384 times)

0 Members and 1 Guest are viewing this topic.

Offline DanChen2014

  • Regular Member
  • ***
  • Posts: 19
  • Mole Snacks: +1/-1
Re: how to figure out the concentration??
« Reply #15 on: March 12, 2014, 11:51:20 AM »
In this case, you have to consider the weak acid effect.

C6H8O6 + H2O ::equil:: C6H7O6- + H3O+     pKa= 4.1

X2/(0.05×50×10-3-X)=10-4.1

X=4.08×10-4 M

[C6H8O6 ]=(0.05×50×10-3)-4.08×10-4=2.09×10-3 M
« Last Edit: March 12, 2014, 12:07:01 PM by DanChen2014 »
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27894
  • Mole Snacks: +1816/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: how to figure out the concentration??
« Reply #16 on: March 12, 2014, 01:27:56 PM »
You are contradicting yourself. If you want to that nitpicky you should not treat the initial solution as 50 mM, as acid in it is dissociated too.
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline DanChen2014

  • Regular Member
  • ***
  • Posts: 19
  • Mole Snacks: +1/-1
Re: how to figure out the concentration??
« Reply #17 on: March 12, 2014, 09:47:53 PM »
Quote from: Borek on March 12, 2014, 01:27:56 PM
You are contradicting yourself. If you want to that nitpicky you should not treat the initial solution as 50 mM, as acid in it is dissociated too.

Just because in this case, the effect can not be ignored. 50mM was given, I assumed that was the real concentration.

Anyway, I will not post this kind of answer any more. Sorry for anything I have done which may not follow the forum's rule.
Logged
Pages: 1 [2]   Go Up
« previous next »
Sponsored Links