# Dilution calculations help

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#### GilaMinumBeer

##### Half-fast Prattlarian
HBT Supporter
I am looking at a product,

128 Ounces (1 Gallon) of 46% Phosphoric Acid.

The suggested dilution is at 2 Gallons or 6 Gallons. My challenge here is to determine the percentage of PA at dilution. How do I calculate this to the suggested dilution (assuming neutral water used)?

Not sure what you're looking for?

1 gallon 46% Phosphoric Acid + 1 Gallon Water = 2 Gallons 23% Phosphoric Acid
1 gallon 46% Phosphoric Acid + 5 Gallon Water = 6 Gallons 7.6% Phosphoric Acid

Is that what you were looking for?

What concentration are you looking for?

Doh. Sorry.

The suggested dilutions are 1 ounce per 2 gallons or, 1 ounce per 6 gallons.

Ok I'll get back once I convert to metric...

Edit:

If my converstion is right

1oz in 2 gallons is 0.18% Phosphoric Acid
1oz in 6 gallons is 0.06% Phosphoric Acid

Thanks. I am blundering my way to the same numbers.

Not sure what you're looking for?

1 gallon 46% Phosphoric Acid + 1 Gallon Water = 2 Gallons 23% Phosphoric Acid
1 gallon 46% Phosphoric Acid + 5 Gallon Water = 6 Gallons 7.6% Phosphoric Acid

Is that what you were looking for?

What concentration are you looking for?

Here is a generic solution:

(Vi ) x (%i ) = (Vf ) x (%f )
where Vf = Vi + Vdilution
Vf = final volume
Vi = initial volume of phosphoric acid used
%i = percent phosphoric acid in initial volume
%f = percent phosphoric acid after dilution
Vdilution = volume of water added

Always add acid to water. This will work regardless of units (metric or Brittish)

Here is a generic solution:

(Vi ) x (%i ) = (Vf ) x (%f )
where Vf = Vi + Vdilution
Vf = final volume
Vi = initial volume of phosphoric acid used
%i = percent phosphoric acid in initial volume
%f = percent phosphoric acid after dilution
Vdilution = volume of water added

This is the same as C1V1 = C2V2
C = Concentration
V = Volume

So:

46 X 1 = C2 X 257 (for 1 oz. per 2 gallon)
C = .18%

Loweface already got it, but I thought it was worth posting the equation because it is very valuable in brewing.

That's esentially how I did it I just don't know how many oz in a gallon

Yes always, add Acid to Water!! I can't stress that enough. Adding acids to H20 causes a rapid shift in pH. While you're only working with a small concentrations, it also causes exothermic reactions to occur (i.e....the temp. of the solution increases as well). It's not mandatory, but it's a safety thing. Good Advice LASTNHOVGATOR.

That's esentially how I did it I just don't know how many oz in a gallon

Welcome to the American system of weights and measures.

1 pint = 16 oz is common knowledge for beer drinkers (a regular bottle of beer is 12oz)

2 cups = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon

Easy-ish to remember: 2 except the quart is short for quarter so there's 4 of them in the next size.

Now, with smaller volume measure it gets weird ( 3 teaspoons = 1 tablespoon, 16 tablespoons = 1 cup).

And the British system is different. A British pint is 20 oz. From there it's still 2 pints in a quart, 4 quarts in a gallon, so a British quart or gallon is obviously bigger than an American quart or gallon.

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