We are doing a simple water electrolysis experiment but I have issues with the electrolyte solution.
Took 450ml of distilled water and slowly dissolved 50g of NaOH until heating ceased. If I'm not wrong that should be a 10% solution (in weight) and about 2.5M.
From this resource the electrical conductivity should be about 309 mS/cm, so 3.2 Ohm×cm; this seems consistent given that electrolysis uses a lot of current.
However with the highly non-scientific method of dipping the DVM probes in the solution I see more than 20 kOhm resistance, which is nowhere near what I'm expecting (sorry, no specialized equipment there). And, of course, the experiment fails (no significant current drawn)
Am I doing something wrong?
I fear that the sodium hydroxide is degraded (it's hardware store grade flakes, supposedly 98%), given that the bottle was not sealed (only a child proof cap, but not airtight). I know that it absorbs CO2 from the air but I've no idea of how much can influence it.