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How to can ı make a 50/50 mix of distilled water and isopropyl alcohol?

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ink555:
Hi, it may sound dumb if I fill half of the bottle with distilled water and the other half with isopropyl alcohol, will I get a 50/50 mix of distilled water and isopropyl alcohol? Or do I need to do something else as well? I will use this mix to clean my monitor.

Borek:
Ignoring some nitpicking (50/50 is ambiguous, as it can be 50/50 volume by volume or weight by weight, these are different things) yes, mixing equal volumes of water and isopropyl alcohol will produce a solution good enough for the intended purpose.

ink555:

--- Quote from: Borek on February 25, 2023, 03:45:48 AM ---Ignoring some nitpicking (50/50 is ambiguous, as it can be 50/50 volume by volume or weight by weight, these are different things) yes, mixing equal volumes of water and isopropyl alcohol will produce a solution good enough for the intended purpose.

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I think by saying 50/50, the user manual says there should be an equal amount of water and isopropyl alcohol. In other words, imagine that I have a 500 ml bottle. In order to create a 50/50 mixture of water and isopropyl alcohol, I should add 250 ml water and 250 ml isopropyl alcohol into that bottle.

Borek:

--- Quote from: ink555 on February 26, 2023, 08:13:01 PM ---I think by saying 50/50, the user manual says there should be an equal amount of water and isopropyl alcohol. In other words, imagine that I have a 500 ml bottle. In order to create a 50/50 mixture of water and isopropyl alcohol, I should add 250 ml water and 250 ml isopropyl alcohol into that bottle.
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That's what I referred to by "mixing equal volumes", 250 mL is identical to 250 mL ;) And that produces solution that is said to be 50/50 by volume.

But: approaching the problem this way there is no guarantee you will get 500 mL of the solution, most likely you will get a bit less, which makes the situation a bit awkward.

If you mix 50 mL of A and 50 mL of B and you get 100 mL then the meaning of 50/50 is obvious. But when you mix 50 mL and 50 mL and you get 98 mL it is not. Where is the missing 2 mL?

For most practical applications it doesn't matter, for precise calculations it is quite important.