Hey! Sign in to get help with your study questionsNew here? Join for free to post

Acids Question

Announcements Posted on
How often do you go out? 11-02-2016
How proud of your uni are you? Take our survey for the chance to win a holiday! 09-02-2016
  1. Offline

    ReputationRep:


    Hey I've done this question and just want to make sure I followed it correctly. I can't get the markscheme as the OCR site is down and my files have been mixed up but here's my method:

    n=m/M so do 72.9/45 = 1.58mol

    apply n=c*v/1000 to get the concentration by rearranging therefore c = 2.10moldm^-3

    Apply the Ka formula:
    Ka = [CH3OO-][H+]/[CH3COOH]

    Plugged the values in and got [H+] to be 5.97*10^-3
    Converted it into pH and got the pH of 2.22

    If anyone can be kind enough to check it for me, I'll really appreciate it
  2. Offline

    ReputationRep:
    (Original post by LifeIsGood)


    Hey I've done this question and just want to make sure I followed it correctly. I can't get the markscheme as the OCR site is down and my files have been mixed up but here's my method:

    n=m/M so do 72.9/45 = 1.58mol

    apply n=c*v/1000 to get the concentration by rearranging therefore c = 2.10moldm^-3

    Apply the Ka formula:
    Ka = [CH3OO-][H+]/[CH3COOH]

    Plugged the values in and got [H+] to be 5.97*10^-3
    Converted it into pH and got the pH of 2.22

    If anyone can be kind enough to check it for me, I'll really appreciate it
    Error in red.

    NOTE : Your method is correct.... Just change that small error in the beginning
  3. Offline

    ReputationRep:
    (Original post by LifeIsGood)


    Hey I've done this question and just want to make sure I followed it correctly. I can't get the markscheme as the OCR site is down and my files have been mixed up but here's my method:

    n=m/M so do 72.9/45 = 1.58mol
    the relative mass of ethanol is 46

    79.2/46 = 1.72 mol


    apply n=c*v/1000 to get the concentration by rearranging therefore c = 2.10moldm^-3
    if 1.72 mol is in 0.75 litres the concentration is 1.72/.75 = 2.30 M



    Apply the Ka formula:
    Ka = [CH3OO-][H+]/[CH3COOH]

    Plugged the values in and got [H+] to be 5.97*10^-3
    Converted it into pH and got the pH of 2.22

    If anyone can be kind enough to check it for me, I'll really appreciate it
  4. Offline

    ReputationRep:
    Thanks for the quick replies! Small error on my part, glad I got it right. Thanks again!

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: April 22, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Today on TSR

Student Money Week continues...

Find out which Q&As are happening today

Poll
Do you listen to podcasts?
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.