I got some phosphoric acid for carbonate reduction in my liquor. The strength should be 75%, but from the experimentation I've done so far it seems a little higher than that.
My main issue with it is that at that strength it's difficult to measure the correct amount for my liquor as even with 250ppm alkalinity I'm only adding a few ml of acid.
I was thinking that if I took 50ml of acid and mixed it into 450ml of deionised water I would end up with something closer to a 7.5% strength solution, which would be easier to measure out on my brew days.
Will this work, or will the dilution destabilise the acid over time, limiting its shelf life?
My alternative is just to buy some small pipettes for more accurate measuring.
Diluting Phosphoric Acid
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Jocky
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Diluting Phosphoric Acid
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.
Re: Diluting Phosphoric Acid
It's fine... It's fairly stable stuff. I would dilute to a reasonable strength - maybe like CRS (so 3 - 4 Molar phosphoric)
A useful density/ concentration table is below
http://www.handymath.com/cgi-bin/phostb ... bmit=Entry
How much are you overshooting by, how are you taking your measurements and how accurate are they ?
A useful density/ concentration table is below
http://www.handymath.com/cgi-bin/phostb ... bmit=Entry
How much are you overshooting by, how are you taking your measurements and how accurate are they ?
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Jocky
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Re: Diluting Phosphoric Acid
That's a useful table, thanks.
Part of the issue is certainly the resolution of my measuring equipment - I started off with a 100ml measuring cylinder. I need something finer than that to start off with.
Part of the issue is certainly the resolution of my measuring equipment - I started off with a 100ml measuring cylinder. I need something finer than that to start off with.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.
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Aleman
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Re: Diluting Phosphoric Acid
Why not a 10ml syringe from a chemist.
Definitely dilute it, at least by a factor of 10.
For the acids I use (Hydrochloric and Sulphuric) I dilute the hydrochloric to 2Molar and the sulphuric to 1Molar. My reasoning is that hydrochloric is monoprotic, it supplies 1 hydrogen ion, and sulphuric is diprotic, supplying 2 hydrogen ions, therefore, the solutions are equivalent in terms of the amount of bicarbonate they remove.
Now while phosphoric is triprotic, supplying 3 hydrogen ions, for our purposes at the typical pH of the mash it must be considered monoprotic
Definitely dilute it, at least by a factor of 10.
For the acids I use (Hydrochloric and Sulphuric) I dilute the hydrochloric to 2Molar and the sulphuric to 1Molar. My reasoning is that hydrochloric is monoprotic, it supplies 1 hydrogen ion, and sulphuric is diprotic, supplying 2 hydrogen ions, therefore, the solutions are equivalent in terms of the amount of bicarbonate they remove.
Now while phosphoric is triprotic, supplying 3 hydrogen ions, for our purposes at the typical pH of the mash it must be considered monoprotic
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Wonkydonkey
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Re: Diluting Phosphoric Acid
Aleman, I like your simplicity, easy for everyone to understand.
also for everyone to understand. use a 10ml not a bigger or smaller syringe as the errors will be bigger
also for everyone to understand. use a 10ml not a bigger or smaller syringe as the errors will be bigger
To Busy To Add,
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Jocky
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Re: Diluting Phosphoric Acid
Quick math check please.
250ml of the solution I have weighs 406g (1.624g/ml)
Using the calculator that killer posted, it suggests that means I have a 78.8% solution by weight.
With phosphoric acid having a molar weight of 98g/mol, to get to a 1 Molar solution of 1 litre I would need to add 1 mol to water to make up 1 litre.
That would be (98/0.788 =) 130.7grams of my acid solution, or (130.7 / 1.624 =) 80.5ml by volume to (1000-80=) 920ml of water.
250ml of the solution I have weighs 406g (1.624g/ml)
Using the calculator that killer posted, it suggests that means I have a 78.8% solution by weight.
With phosphoric acid having a molar weight of 98g/mol, to get to a 1 Molar solution of 1 litre I would need to add 1 mol to water to make up 1 litre.
That would be (98/0.788 =) 130.7grams of my acid solution, or (130.7 / 1.624 =) 80.5ml by volume to (1000-80=) 920ml of water.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.
. . . at 20C of courseRe: Diluting Phosphoric Acid
That's about right.
Just as a ballpark figure, 75% phosphoric is 12.05 Molar - so 83 mL of that made up to 1L would be 1 Molar.
Does that tie in with the discrepancy you were measuring ? (it's not a massive error - about 5% off advertised)
Of course - and I hate to say this, how accurate was your volume measurement, and your weight measurement ?
I'm sorry if I sound like a pedantic Pete but I'm doing so for a reason. Now this is well out of the scope of your question, but, in relation to what Aleman mentioned a minute ago, phosphoric acid is polyprotic (has three protons), and in most calculators is considered to give 1 proton per molecule of acid and so neutralises 1 molecule of Bicarbonate. There is an argument to suggest that it is capable of giving more than 1 proton (in fact I've read 1.2 protons). So my question was really in relation to finding evidence supporting (or disproving) that.
Apologies if I've sent you to sleep...
Just as a ballpark figure, 75% phosphoric is 12.05 Molar - so 83 mL of that made up to 1L would be 1 Molar.
Does that tie in with the discrepancy you were measuring ? (it's not a massive error - about 5% off advertised)
Of course - and I hate to say this, how accurate was your volume measurement, and your weight measurement ?
I'm sorry if I sound like a pedantic Pete but I'm doing so for a reason. Now this is well out of the scope of your question, but, in relation to what Aleman mentioned a minute ago, phosphoric acid is polyprotic (has three protons), and in most calculators is considered to give 1 proton per molecule of acid and so neutralises 1 molecule of Bicarbonate. There is an argument to suggest that it is capable of giving more than 1 proton (in fact I've read 1.2 protons). So my question was really in relation to finding evidence supporting (or disproving) that.
Apologies if I've sent you to sleep...
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Jocky
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Re: Diluting Phosphoric Acid
Zzzzzzzzzz...
I joke. My measurements are actually based upon the product sheet I found for the acid, and I wanted to do some back of the fag packet sums to check what I was planning and that my GCSE chemistry holds up.
Now I need to get appropriate measuring and storage equipment.
I joke. My measurements are actually based upon the product sheet I found for the acid, and I wanted to do some back of the fag packet sums to check what I was planning and that my GCSE chemistry holds up.
Now I need to get appropriate measuring and storage equipment.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.