I should just add that Ohm's Law is not a true law as such, as there are circumstances in which it completely breaks down. But it does work well generally.
Furthermore, I'll make an apology here and add something that I did not know or realise. That is, that an electrolyte does not follow Ohm's Law. Well you learn something every day!
That is not to say that the expression V = I x R does not apply, but rather that the wording of Ohm's Law states that the resistance must remain constant regardless of the applied voltage or current flow. Basically then anything that shows a non-linear curve of V against I, such as an electrolyte or a semiconductor (temperature coefficeints not withstanding) is considered not to follow Ohms Law... or is said to be non-ohmic. And I have to say in all my years I'd never heard the term non-ohmic before - even though I studied semiconductor principles in the distant past.
The main problem then with electrolyte resistance and indeed why you cannot give it a fixed figure is because it varies with voltage and current. That said, for any given values of voltage and current flow, you can determine the resistance from V/I = R. It's just that unlike a resistor which maintains its value irrelevant of current and voltage, as soon as you take the voltage off an electrolyte, the resistance changes.
Must be getting a little complacent in my old age!