Australia's Science Forum

We recently received a set of the WiFi pH probes, which are fantastic, the seniors have been using them non-stop. We need to top up the buffer solution and according to the documentation it's a 4M solution of potassium chloride, mixed with a pH 4 buffer solution as well as a few drops of pH buffer preservative. I am not having much success with the KCl - it is not dissolving. Has anyone else made up their own solution? Any ideas?
Thanks!

I usually just wack it on the magnetic stirrer and leave it for a while. It eventually dissolves (That's my default with most things, then I add heat if it's not dissolving or leave overnight)

Thanks linotas - I will persist....

i've made it before, definitely need to leave it stirring over night sorry. Do you have a magnetic stirrer? set and forget

While I was researching the buffer solution, I found out how to make standard pH buffer solutions, might be of interest if you need one in a hurry?

(All values assume a calibration temperature of 25 Celsius.)
 pH 4.00 buffer solution: 100 mL of 0.1 M Potassium Hydrogen Phthalate + 0.2 mL of 0.1 M HCl
 pH 7.00 buffer solution: 100 mL of 0.1 M KH2PO4 + 58.2 mL of 0.1 M NaOH
 pH 10.00 buffer Solution: 100 mL of 0.025 M Na2B4O7.10H2O (Borax) + 36.6 mL of 0.1 M NaOH

And to then make up the buffer solution for the Pasco WiFi pH probes -
pH Probe storage solution:
Add 1g KCl to 100ml of pH4 buffer solution

Prima, could you please tell me about the Pasco probe - is it an independent unit or does it have to connect to a data logger? Could you please tell me where you purchased it from and the price?
Thanks

We bought the Pasco pH probes from CiderHouseTech. They are WiFi and/or Bluetooth, seem really easy to use. They are not cheap (about $150 each) but don't need any additional interface at all, they download an app to their phones and connect directly to a specific probe.

Hopefully this link will work, but if not you'll be able to find them quite easily. The US Pasco website has a lot more information - YouTube videos, blogs, downloads, manuals etc.

http://probes.ciderhousetech.com.au/ind ... 7-06-16-17

Thanks. I will have a look at their website.