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Question 934237: what is the equation to make 350 gallons (water level can vary) of water a 5% HCL solution using 32% HCl acid. How much 32%HCL acid I would add to a water level to achieve a 5%HCL total Solution.
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! I have no idea what math teachers' answers would be, but I would bet that they would be wrong. For starters, what do they mean by 32% HCl, and what do they mean by 5% HCl?
When I buy hydrochloric acid solution for the lab, it comes in a bottle whose label states something like "assay ... 35.9%" and that means that there are 35.9 grams of HCl in 100 grams of solution.
When someone tells me to make a 5% solution of HCL,
they precisely specify whether they want a 5% (w/w) solution (5% by weight),
containing a 5 gram mass of HCl in a 100 gram mass of solution,
or they want a 5% (w/v) solution,
which would contain 5 grams of HCl in 100 milliliters of solution.
If it is not specified, the percent is percent by weight.
A math teacher may think 32% HCl is 32 grams HCl in 100 mililliters of solution. Hopefully, no one would think it means 32 liters HCl in 100 liters of solution, because HCl is a gas, and the volume of any amount of gas changes with temperature and pressure.
No one would
1) measure 32 liters of HCL gas measured at a certain temperature and pressure,
2) dissolve it in water and dilute it to 100 liters, and
3) then call that 32% HCl.
THE CHEMICAL ENGINEER ANSWER:
It could be that you have a concentrated hydrochloric acid solution containing 32% HCl by weight. We would call that solution concentrated hydrochloric acid, while hydrogen chloride is what we call HCl gas, when we buy it in a small gas cylinder for chemical synthesis purposes.
Such a solution would have 32 grams of HCl gas and 68 grams of water in a 100 gram amount of solution.
At   a 32% HCl by weight solution will have a density of 1.593 grams per milliliter,
so 100 grams of solution would have a volu,me of
 .
A 5% solution by weight would contain 5 gram HCl in a total of 100 grams of solution (5 grams HCl and 95 grams of water), and at would have a density of 1.02563 grams per milliliter. As a consequence the 100 grams of solution would have a volume of 97.5 milliliters.
A gallon is 3.785 liters, or 3785 milliliters, so a volume of 350 gallons is
 or  .
A volume of 350 gallons of a 5% by weight HCl solution would weigh
and to make that much solution you would need
 of HCl,
which will be contained in
 of your concentrated solution.
You will not weigh it (too dangerous, horrible corrosive fumes), so you will need to measure it by volume.
The volume you need to measure is
That amount (212.3kg, 133.269L) of concentrated acid will have the 67.9kg HCl you need plus a good amount of water.
The amount of water in that much concentrated acid is
 .
You will need to mix that concentrated acid with some extra water to obtain the 1358.7kg total weight of solution.
How much water will you mix with 212.3kg concentrated acid?
 .
At , pure water has a density of 0.9982343g/mL=0.9982343kg/L, so that mass of water will have a volume of
So you would measure 1148.4 liters of water,
slowly add 133.3 liters of concentrated acid, while stirring,
and after the mixture cools back to ,
you will have the 1324.75L (350 gallons) of 5% by weight acid that you wanted
The volumes you added add up to  , but volume is not additive when you are mixing chemicals.
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