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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: juliusdarius on August 31, 2014, 08:53:47 PM

Title: Amount of HCl needed given density and percent?
Post by: juliusdarius on August 31, 2014, 08:53:47 PM
How much concentrated hydrochloric acid solution (36.0% HCl by mass, d = 1.18g/mL), in milliliters, is required to produce 11.5L of 0.276M HCl?

Work: 11.5L(0.276moles HCl/1 Liter)(36.461g/1mol HCl)(1mL/1.18g)*0.36=35.08mL. This is the answer I received but it is not correct. The big problem I am having is working the 36% into the unit analysis.

Thanks for the help
Title: Re: Amount of HCl needed given density and percent?
Post by: Vidya on August 31, 2014, 11:34:09 PM
36% by mass means 36% of 1.18 g per mL is due to HCl
so mass of HCl in 1mL = 0.36*1.18 g --> convert this into moles and then that much number of moles are present in 1mL ---convert this into molarity
Now you have the molarity of the given solution and you need to know how much volume is needed to get the desired solution   11.5L of 0.276M HCl
use dilution law
M1V1=M2V2
M1 and V1 is the given solution molarity and volume
M2 and V2 is the desired solution.
Check your answer.I am sure you will get correct answer.