Results are out! Find what you need...fast. Get quick advice or join the chat
Hey there Sign in to join this conversationNew here? Join for free

Calculating pH of a Weak Acid

Announcements Posted on
Applying to Uni? Let Universities come to you. Click here to get your perfect place 20-10-2014
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    Could somebody please answer this question for me and show me your working so I can hopefully see how it's done? I'm fine with strong acids that completely ionise but I'm struggling with weak acids.



    Calculate the pH of 0.01 mol.dm-3 propanoic acid (a weak acid, which partially ionises and has a dissociation constant of 1.34 x 10-5 mol.dm-3) at 298K.
    • 22 followers
    Offline

    ReputationRep:
    (Original post by TFish89)
    Could somebody please answer this question for me and show me your working so I can hopefully see how it's done? I'm fine with strong acids that completely ionise but I'm struggling with weak acids.

    Calculate the pH of 0.01 mol.dm-3 propanoic acid (a weak acid, which partially ionises and has a dissociation constant of 1.34 x 10-5 mol.dm-3) at 298K.
    Do you know the formula for the dissociation of a weak acid?

    ka = [H+][A-]/[HA]

    assume [HA] is constant
    • 0 followers
    Offline

    ReputationRep:
    (Original post by charco)
    Do you know the formula for the dissociation of a weak acid?

    ka = [H+][A-]/[HA]

    assume [HA] is constant
    This plus the fact that [H+]=[A-]

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: June 28, 2012
New on TSR
Article updates
Reputation gems:
You get these gems as you gain rep from other members for making good contributions and giving helpful advice.