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Hanna pH meters/testers

Discussion in 'Science' started by bogstandardcomp, Jul 12, 2011.

  1. bogstandardcomp

    bogstandardcomp New commenter

    As our budget is pretty tight this year I am thinking of purchasing the cheapish Hannah pH testers, @ £32 for student use at A level.

    Our techy says they are rubbish, any thoughts or experience of using them
     
  2. bogstandardcomp

    bogstandardcomp New commenter

    As our budget is pretty tight this year I am thinking of purchasing the cheapish Hannah pH testers, @ £32 for student use at A level.

    Our techy says they are rubbish, any thoughts or experience of using them
     
  3. phlogiston

    phlogiston Star commenter

    They worked OK for us for a number of years, but currently need new electrodes.
    Unfortunately, while I was on extended sick leave, one of our technicians did not understand the need to keep the business end in KCl. Better a cheap meter than an expensive one!
    P
     
  4. When these Hanna Checkers first came out in the nineties,
    there was a problem of quality control but in recent years they have become much
    better. I have kept mine in KCl solution but because they are not used that
    often, I found mould growing around the glass electrode which affected
    performance. I now do not put them in any solution, just put the cap on. They
    have a shelf life of about 2 years after which you can replace the bottom part
    (but this is the expensive part, like ink for printers!) They need to be calibrated
    before using in the 7 to 4 or 7 to 10 range. A normal pH probe is about £60 and
    then there is the cost of the meter. An advantage of the Checker is that it
    fits into a test tube or a the well-plate of a Combo-plate. I also put a
    plaster over the second digital place. Pupils worry as this number keeps
    changing and then say “it’s not accurate!”
    <font size="3" face="Times New Roman">

    </font>But what do you use them for at KS3 and 4? That is the
    important thing. Because pH is a log scale, (pH=-log10[H+]), there is very
    little understanding of the concept. When trying to make salts, some fret over
    the issue getting the pH to exactly 7, which is difficult. A pH between 5 and 9
    is quite adequate when making salts (but it is not what the text book says!)
    <font size="3" face="Times New Roman">

    </font>
     
  5. bogstandardcomp

    bogstandardcomp New commenter

    Tks for the help, keep it coming. We need it for KS5 biology, the practical exam this year was a massive headache without ph meter.
    I also spoke to a Hanna person who also said the Checker1 @ &pound;31 with the replacable electrode is the best option for student use . Replacement electrodes are &pound;20.

    He said they will all get knackered if the electrodes are not looked after no matter what the price of the meter, the mould issue is something we will certainly think about. Cheers to all contributors
     

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