# How can I identify whether a substance is KOH or NaOH?

I've bought $\ce{NaOH}$ or $\ce{KOH}$ (I don't remember which one!) for my electrolyzer and I've tested it. Now I want to improve its performance and I was searching for a better electrolyte when I realized I've forgotten what my current electrolyte is! It is white and has crystal shape, but which one is it, $\ce{KOH}$ or $\ce{NaOH}$? If they are both white how can I know?

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I edited your title to make the question a little more specific. I also suggest that you remove the last three sentences and make them a separate question - it will be easier to get an answer that way. –  thomij Aug 5 '14 at 17:09
I'm sorry to say, you won't improve your mileage by using your alternator to electrolyse water then burning the hydrogen produced. Given the efficiency of the engine/alternator/electrolyser, you'll be lucky to get 1 litre of electrolytically produced hydrogen for every 5 litres of hydrogen (or the gasoline equivalent thereof) burned in your engine. –  steveverrill Aug 5 '14 at 21:17