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Standarization of a Sodium Hyrdoxide Solution

  1. Jan 5, 2015 #1
    1. The problem statement, all variables and given/known data
    Hello, I missed a lab before the break because I was really sick and I need help. I was given the data from my partners for the titration lab and I don't understand how to calculate the amount of potassium hydrogen phthalate used in each trial, amount concentration of the sodium hydroxide solution and the average concentration of the solution. Thanks in advance.
    They used .5g of KHP.

    Trials(mL)
    1 2 3
    Initial volume of NaOH: 0 | 5.8 | 12.2 |

    Final volume of NaOH: 5.8 | 12.2 | 17.3 |
    Total Volume: 5.8 | 6.4 | 5.1 |

    2. Relevant equations
    c=n/v, n=m/mm c1v1=c2v2

    3. The attempt at a solution
    When they say amount do they mean g or moles?
    n=m/mm
    n=.5/204.22
    n=0.002448
    Do I use the final volumes to calculate amount concentration?
     
  2. jcsd
  3. Jan 5, 2015 #2

    epenguin

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    Homework Helper
    Gold Member

    Nobody can answer that nor should try because it is far too vague and unclear.
    "They used 0.5 g of KHP". To do what?
    OK it looks like like they used 3 volumes of the NaOH solution to titrate each time the same unstated volume of a KHP solution that was made up in unstated way from 0.5 g. KHP.
    That's what you use KHP for, because you can do it precisely ("primary standard") as your book or manual certainly explains (though that precision is rather wasted given your colleagues' poor reproducibility!)
    From the titrations you can deduce, within the said loose limits of their precision, the molarity of the NaOH.
    That is very likely the object lf the experiment so you are asking the wrong question to the wrong people - your colleagues should tell you what they did with the KHP.
     
  4. Jan 6, 2015 #3

    Borek

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    Staff: Mentor

    It is not something you should calculate - it is something that should be measured (and precisely!) before the titration. As epenguin signaled, KHP is one of these substances that can be prepared very pure and weighed very accurately.
     
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