# Math/system check (lactic acid amounts by weight)

I’m updating my water report info and tweaking a few things in my brewing calculations.
I just want to make sure I’m calculating this part right as I’m not much for math and prefer to let the programs do it.
I could even have the values wrong for all I know.

I weigh everything and for mineral additions I have a gram scale that measures to the hundredth. I also weigh my 88% lactic acid.

If Bru’n Water suggests a 3mL addition of 88% lactic acid, I use the following info:
Assuming "A weight measure of liquids can be used if the density of the liquid is known. Divide the calculated liquid volume by the liquid’s density to determine the weight of liquid needed." (-Martin Brungard)
Assuming “88% lactic acid has a density of about 1.206 g/cc at room temperature.” -(A.J.deLange)

I end up w/ 2.48 grams unless I’m missing something.

Maybe I’m remembering 7th grade chemistry wrong but I thought it would go like this:

x / 3ml = 1.206 g/ml

So solving for x we would multiply both sides by 3ml leaving us with x = 3.618g

All that said, just go to your local pharmacy and ask for a cough syrup dosing syringe. They are free and measure up to 5ml. If you want something more accurate insulin syringes measure up to 1ml but with more graduated marks.

[quote=“mattnaik”]Maybe I’m remembering 7th grade chemistry wrong but I thought it would go like this:

x / 3ml = 1.206 g/ml

So solving for x we would multiply both sides by 3ml leaving us with x = 3.618g[/quote]
That’s what I thought too…of course my first thought was why not just use a syringe or one of those spoons for measuring baby meds.

edit: Matt beat me too it…

Did I mention I was bad at math?

So I’m just multiplying the liquid volume by the liquids density?
Martin’s use of division went over my head.

I just may do that and eliminate the equation but I need to know the correct math to go back and compare to my results.

Thanks for the help.

Well, here’s a first. But I might just be a broken clock.

More google-fu turned up this site: http://www.thecalculatorsite.com/conver … volume.php
They don’t have 88% Lactic acid listed that I could find so I just entered the density.

=2.48 grams

I think I may still head to the pharmacy anyway.

[quote=“dsiets”]Well, here’s a first. But I might just be a broken clock.

More google-fu turned up this site: http://www.thecalculatorsite.com/conver … volume.php
They don’t have 88% Lactic acid listed that I could find so I just entered the density.

=2.48 grams

I think I may still head to the pharmacy anyway. [/quote]

Or go to the local supermarket and get a 30ml turkey basting syringe. They usually come with a long needle which is handy for reaching into a partially depleted bottle of liquid. The one I have is graduated in 1ml increments, so it’s pretty easy to measure within .5ml, which is generally adequate accuracy for 5 gallon batches. Even if you’re dealing with smaller amounts (as you currently are) you can get the smaller syringe from the pharmacy and the larger basting syringe will still come in handy at some point in your brewing career. I use mine every time I brew.

[quote=“dsiets”]Well, here’s a first. But I might just be a broken clock.

More google-fu turned up this site: http://www.thecalculatorsite.com/conver … volume.php
They don’t have 88% Lactic acid listed that I could find so I just entered the density.

=2.48 grams

I think I may still head to the pharmacy anyway. [/quote]

That’s converting weight to volume not volume to weight.

So if you had 3 grams of lactic, it would be 2.48 mL volume. You had it backwards.

[quote=“mattnaik”][quote=“dsiets”]Well, here’s a first. But I might just be a broken clock.

More google-fu turned up this site: http://www.thecalculatorsite.com/conver … volume.php
They don’t have 88% Lactic acid listed that I could find so I just entered the density.

=2.48 grams

I think I may still head to the pharmacy anyway. [/quote]

That’s converting weight to volume not volume to weight.

So if you had 3 grams of lactic, it would be 2.48 mL volume. You had it backwards.[/quote]

HA!
Good catch. When I plugged in “volume to weight” in google and that popped up, I scrolled right on down past the Bold “Weight to Volume”.
So I’m wrong once again. Thanks for keeping me straight.

On the way past Walgreens I ran and picked up a 5 mL syringe. I give up. I’m grabbing a beer. :mrgreen: