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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: DanjtoUru on July 10, 2019, 07:41:47 PM

Title: Ethanol 99.5 percent to 88
Post by: DanjtoUru on July 10, 2019, 07:41:47 PM

If I have 99.5 percent pure ethanol, how can I get it to 88 percent?
What amount of water is necessary?

Title: Re: Ethanol 99.5 percent to 88
Post by: Borek on July 11, 2019, 03:08:55 AM

You have to show your attempts at solving the problem to receive help, this is a forum policy.

Hint: you will either need densities to solve the problem in terms of solution volumes, or you can reasonably easily solve the problem using solution masses. Imagine starting with 1 kg of solution  - what mass of ethanol does it contain? What should be the mass of the final solution so that given mass of ethanol is 88% of that?

Title: Re: Ethanol 99.5 percent to 88
Post by: DanjtoUru on July 11, 2019, 09:35:01 AM

Sorry for that,
I use C1.V1=C2.V2, i need to make 1000liters of 88% ethanol
The ethanol have 99.5 (that is on the data analysis sheet)
I try with that so i add like 885 lts of ethanol and the rest of water but when i analyze it, it has like 93%

Title: Re: Ethanol 99.5 percent to 88
Post by: Corribus on July 11, 2019, 10:39:01 AM

How are you doing your dilution and how are you analyzing the resulting solution?

Title: Re: Ethanol 99.5 percent to 88
Post by: Borek on July 11, 2019, 02:48:19 PM

Quote from: DanjtoUru on July 11, 2019, 09:35:01 AM

I use C1.V1=C2.V2

That works for molar concentrations, not for w/w percentages.