Diluting alcohol solution

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amr638

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Diluting alcohol solution

I need to make 240 mL. of solution that contains 20% of alcohol. How many mL. of 70% alcohol do I need to use?

Posted 149 day ago

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Answers (4)

amr638

Thank you guys! I understand it now. Thank you very much. I appreciate the answers! (and the tip)

Posted 148 day ago

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Lee

Things you know and can use
Your final volume 240 mls
Your final alcohol concentration at your final volume is 20%
100 mls of your 70% concentrate contains 70 mls of alcohol and 30 mls of water

You need to to first calculate 20% of 240 mls

240 * .20 = 48 mls (of 100 % alcohol)

Then you need to divide 48 by .70 (the 70% concentrate) to find out what volume of your concentrate contains 48 mls of alcohol

48/0.7 = 68.57mls
Finally you need to subtract 68.57 from 240 to find out how much water you need to dilute your 70% to your final volume at the desired percent

240 mls - 68.57 mls = 171.43 mls

You can check your work as well by keeping in mind how much water you bring over from the 68.57 mls of 70 % by difference you have

48 mls of alcohol
20.57 mls of water (68.57 - 48)
These amounts come from your 70% solution

You add 171.43 mls of water

Your total volume is 240 mls so knowing your alcohol volume, now you can always go back and check your percent

48/240 * 100 = 20

Posted 149 day ago

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MFB13

Let x = the number of mL of 70% alcholic water solution needed

then, (0.7 x / 240) = 0.2

solving for x gives about 68.6 mL of the 70% alcholic water solution required.

The rest of the volume is pure water. which is 240 mL - 68.6 mL = 171.4 mL

good luck...

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matherapist

There are two parts to the answer.
First, find out how much alcohol is needed to give a 20% solution in 240 ml. That is 20% 0f 240 or 48ml.

Then you need to figure out how much of a 70% solution of alcohol is needed to give 48ml of alcohol.
this means that if x is the amount of solution, then .7x=48 or x=68.57 ml of 70% solution.

The amount of non alcohol bearing solution is 240-68.57 = 171.43

A word of advice- never mix alcohol with coke or ginger ale or any other suger based soda. It's a sure way to get a hangover.

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