April 25, 2024, 02:09:23 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: MCAT Acid/Base Question  (Read 3358 times)

0 Members and 1 Guest are viewing this topic.

Offline mrlucky0

  • Regular Member
  • ***
  • Posts: 34
  • Mole Snacks: +0/-0
MCAT Acid/Base Question
« on: June 10, 2009, 02:56:20 AM »
Hydrochloric acid is a strong acid. A solution of sodium chloride should have a pH of:

A. less than seven
B. seven
C. more than seven but less than fourteen
D. more than fourteen

The answer is B, but I choose C because:

The conjugate base of a strong acid is a weak base. It follows then, that a solution of chloride ions should be slightly basic: Cl- + H2O = HCl + OH-. Although the equilibrium lies far left, the [OH-] in this situation is still slightly greater than that off 10^-7 M.

Why am I wrong here?
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27663
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: MCAT Acid/Base Question
« Reply #1 on: June 10, 2009, 03:32:59 AM »
Quote from: mrlucky0 on June 10, 2009, 02:56:20 AM
The conjugate base of a strong acid is a weak base.

VERY weak base. Too weak for observable effects.
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline mrlucky0

  • Regular Member
  • ***
  • Posts: 34
  • Mole Snacks: +0/-0
Re: MCAT Acid/Base Question
« Reply #2 on: June 10, 2009, 03:40:03 AM »
Quote from: Borek on June 10, 2009, 03:32:59 AM
Quote from: mrlucky0 on June 10, 2009, 02:56:20 AM
The conjugate base of a strong acid is a weak base.

VERY weak base. Too weak for observable effects.

 Good to know that my intuition of G-chem wasn't flawed. I guess that makes sense now since H2O is a very weak acid relative to Cl-. Still, I hope I don't get a question like this on my actual MCAT.   Thanks.
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links