Phosphoric Acid concentration

[littlewashingtonbrewery]

I recently received some phosphoric acid that was labeled 10%. When I was adding some to my mash water I noticed it looked different but I used the brew software recommended amount anyway. It was much more viscous than the previous bottle that I had gotten a while ago. When I measured my pH it was 4.2. This was after I recalibrated with the appropriate fluids. My meter is a Thermoworks 8689 that I have had for a while and I got a few unusual readings but it has never indicated anything like this. A new probe is being delivered soon.
I am going to taste the beer today since most of the fermentation done. When I tasted the wort before hop addition it didn't taste right but since I seldom do that I don't have much of a baseline.
I have been doing some research about phosphoric acid and have read that the density is a function of the % solution. When I measured the SG using a vial and hydrometer the hydrometer stuck 6" out of the top of the test vial.
My question:
Will I be able to verify or estimate the concentration of the acid I have by measuring the density and/or reverse calculating the actual reading vs the calculated prediction using BruNWater and/or Brewfather? I have been using both for quite a while and generally get good results.
Is there another method such as mixing the acid with distilled or RO water and measuring pH to determine what I have? I would prefer not to test on another batch of beer. I have 4 bottle of this batch of acid and two of them tested the same using the hydrometer.
I contacted the distributor/packager and they say purchasing told them it was the right concentration.

 

[passedpawn]

I recently received some phosphoric acid that was labeled 10%. When I was adding some to my mash water I noticed it looked different but I used the brew software recommended amount anyway. It was much more viscous than the previous bottle that I had gotten a while ago. When I measured my pH it was 4.2. This was after I recalibrated with the appropriate fluids. My meter is a Thermoworks 8689 that I have had for a while and I got a few unusual readings but it has never indicated anything like this. A new probe is being delivered soon.
I am going to taste the beer today since most of the fermentation done. When I tasted the wort before hop addition it didn't taste right but since I seldom do that I don't have much of a baseline.
I have been doing some research about phosphoric acid and have read that the density is a function of the % solution. When I measured the SG using a vial and hydrometer the hydrometer stuck 6" out of the top of the test vial.
My question:
Will I be able to verify or estimate the concentration of the acid I have by measuring the density and/or reverse calculating the actual reading vs the calculated prediction using BruNWater and/or Brewfather? I have been using both for quite a while and generally get good results.
Is there another method such as mixing the acid with distilled or RO water and measuring pH to determine what I have? I would prefer not to test on another batch of beer. I have 4 bottle of this batch of acid and two of them tested the same using the hydrometer.
I contacted the distributor/packager and they say purchasing told them it was the right concentration.

I've done this exact thing by titrating with known acid (or base) until some indicator changes. Phenolphthalein is what I used (cheap on amazon). Carefully measure amounts used. The chemistry math is pretty easy after that. Google it, or post your amts and known concentrations here.

You'll need to create a base of a known concentration, or buy one. NaOH is pretty common. If you don't have any on hand, you should (pretzels and soaping are two reasons ).

 

[balrog]

The phosphoric acid I bought a quart of was 85% and I've always wondered how to easily determine the true %, however, that being said, I just wanted to let you know @littlewashingtonbrewery that 85% is more viscous than water, but not even maple syrup thick. Just more than water. And since my predicted vs measured batches are coming out randomly close to what I expect, I kinda figure it must be close and I haven't gotten too excited about expending energy to find the true percentage.

 

[Silver_Is_Money]

This site will give you Phosphoric Acids percent concentration by density. At room temperature, SG x 0.997 = Density.

Density of phosphoric acid - Steffen's Chemistry Pages

 

[balrog]

This site will give you Phosphoric Acids percent concentration by density. At room temperature, SG x 0.997 = Density.

Density of phosphoric acid - Steffen's Chemistry Pages

Thanks. And at other room temps, USGS has this for that "0.997" factor (my house is more typ at 60-65 than 72-75, but very small diff)
USGS Water Density by Temp

 

[Silver_Is_Money]

10 grams of NaOH (Sodium Hydroxide, or Lye) made up to 250 L in distilled water creates a 1N (one normal) solution of NaOH.

1 mL of a 1N solution = 1 mEq

Phenolphthalein indicator turns pink at around pH 9.

Phosphoric Acid is triprotic, but at pH 9 it is effectively diprotic (as opposed to it being effectively rather close to monoprotic at pH 5.4). At pH 9 the acid strength 10% Phosphoric Acids should be ~2.1325 mEq/mL.

5 mL of 10% Phosphoric Acid x 2.1325 mEq/mL = 10.66 mEq of Acid when at specifically pH 9. This should therefore require 10.66 mL of 1N sodium hydroxide added via slow titration whereby to turn the Phenolphthalein indicator pink, meaning you are at ~ pH 9.

Add 5 mL of 10% phosphoric acid to ~250 mL of distilled water. Add a squirt of Phenolphthalein indicator. Titrate this with 1N sodium hydroxide slowly while mixing until it turns pink. If the titration burrette at this juncture indicates that ~10.66 mL of the 1N sodium hydroxide titrant has been added, then you should have 10% Phosphoric Acid.

Someone please check my work here to verify if I'm getting this correct before anyone attempts this.

 

[balrog]

I was kinda hoping you'd point us to a highly modified Novotny correction equation so we could just use a drop on the refractometer.

I am, if nothing else, somewhat less-than-energetic.

I also seemed to have completely misplaced all my burrettes

 

[Silver_Is_Money]

If 5 mL of 88% Lactic Acid was instead being titrated, then:

1 mL of 88% Lactic Acid has an acid strength of 11.782 mEq/mL at specifically pH 9.

5 mL x 11.782 mEq/mL = 58.91 mEq

It should take 58.9 mL of 1N Sodium Hydroxide to titrate 5 mL of 88% Lactic Acid to pH 9, at which juncture the phenolphthalein indicator will turn pink.

Same procedure as for 10% Phosphoric Acid as seen above, except this time add 5 mL of 88% Lactic Acid to 250 mL of distilled water.

And just as before:
Someone please check my work here to verify if I'm getting this correct before anyone attempts this.

 

[littlewashingtonbrewery]

I've done this exact thing by titrating with known acid (or base) until some indicator changes. Phenolphthalein is what I used (cheap on amazon). Carefully measure amounts used. The chemistry math is pretty easy after that. Google it, or post your amts and known concentrations here.

You'll need to create a base of a known concentration, or buy one. NaOH is pretty common. If you don't have any on hand, you should (pretzels and soaping are two reasons ).

Thank you. I will check into that. I appreciate the resonse!

 

[Silver_Is_Money]

Technically it should be noted that phenolphthalein indicator will begin to turn a faint pink at ~pH 8.3, so in order to hit pH 9, take the titration a wee tad beyond the first stable faint pink achieved while mixing whereby to achieve a bit deeper pink.

 

[Silver_Is_Money]

Thanks. And at other room temps, USGS has this for that "0.997" factor (my house is more typ at 60-65 than 72-75, but very small diff)
USGS Water Density by Temp

I was pulling it in from memory when I stated 0.997. Likely close enough.

 

[littlewashingtonbrewery]

Thank you all for the responses. I really appreciate it! Follow up - I tested and tasted the batch today and the results are outside my 25 years of experience. As I mentioned earlier, the mash pH measured 4.2. I did perform a calibration and it wasn't off very much. I mentioned that my readings have been a little unstable but nothing like this. The new probe will be here soon. I have not had a stalled fermentation since I can remember but this one did it. No more fermentation but the SG tested today at 1.031. The SG when I pitched was 1.053. I use yeast nutrient and I have brewed this recipe many times before. It didn't taste right but it has only been a few days. I am still deciding how to proceed so I appreciate the feedback.

 

[littlewashingtonbrewery]

The phosphoric acid I bought a quart of was 85% and I've always wondered how to easily determine the true %, however, that being said, I just wanted to let you know @littlewashingtonbrewery that 85% is more viscous than water, but not even maple syrup thick. Just more than water. And since my predicted vs measured batches are coming out randomly close to what I expect, I kinda figure it must be close and I haven't gotten too excited about expending energy to find the true percentage.

I attached a picture of the acid I got measured with a hydrometer. You can see the bottle in the picture. Obviously, thicker than water. I am going to measure the density using an accurate scale I have and a graduated cylinder. Someone mentioned Steffen' Chemistry pages and am going to follow-up using the numbers there and correlate it to SG. My pH measurements did not come out right and the beer is not fermenting the way I am used to so something is going on. I am a very experienced brewer and have brewed this recipe many times before. Note: The distributor listed on the bottle repackage what they receive. They have been a good wholesale distributor and I am not trying to make them look bad.

I deleted the picture I originally posted.

 

[littlewashingtonbrewery]

Thanks. And at other room temps, USGS has this for that "0.997" factor (my house is more typ at 60-65 than 72-75, but very small diff)
USGS Water Density by Temp

That is a good page I found almost immediately in my web search. Thanks!

 

[littlewashingtonbrewery]

I've done this exact thing by titrating with known acid (or base) until some indicator changes. Phenolphthalein is what I used (cheap on amazon). Carefully measure amounts used. The chemistry math is pretty easy after that. Google it, or post your amts and known concentrations here.

You'll need to create a base of a known concentration, or buy one. NaOH is pretty common. If you don't have any on hand, you should (pretzels and soaping are two reasons ).

I will google this. I am a retired engineer so I am used to researching problems and figuring things out.

 

[Smiling Frog]

If you have a brix refractometer, take a reading at room temperature. From the Refractometer Brix reading, the weight % phosphoric acid should be:
=1.6027*Bx - 0.001865*Bx^2
where Bx is the Refractometer Brix reading.
At 10%, you should get a reading of about 6.3 Brix.

Above equation should be within +/- 0.1 Wt. Pct.

If you have a refractometer, please post the reading from your sample, and the SG, if you have it.
10% phosphoric acid should have a SG of 1.056 or so. From your picture, I'm going to guess it is much greater than that. Either it isn't phosphoric acid, of they didn't dilute it properly.

Thanks

 

[Vale71]

Thank you all for the responses. I really appreciate it! Follow up - I tested and tasted the batch today and the results are outside my 25 years of experience. As I mentioned earlier, the mash pH measured 4.2. I did perform a calibration and it wasn't off very much. I mentioned that my readings have been a little unstable but nothing like this. The new probe will be here soon. I have not had a stalled fermentation since I can remember but this one did it. No more fermentation but the SG tested today at 1.031. The SG when I pitched was 1.053. I use yeast nutrient and I have brewed this recipe many times before. It didn't taste right but it has only been a few days. I am still deciding how to proceed so I appreciate the feedback.

That's no wonder. Mashing at a PH of 4.2 there is no way you got full conversion of starches as you're almos 1.5 points below optimum PH for alpha-amylase.

 

[Silver_Is_Money]

Viscous (as you have described it) sounds like it potentially may be Lactic Acid.

 

[passedpawn]

Thank you all for the responses. I really appreciate it! Follow up - I tested and tasted the batch today and the results are outside my 25 years of experience. As I mentioned earlier, the mash pH measured 4.2. I did perform a calibration and it wasn't off very much. I mentioned that my readings have been a little unstable but nothing like this. The new probe will be here soon. I have not had a stalled fermentation since I can remember but this one did it. No more fermentation but the SG tested today at 1.031. The SG when I pitched was 1.053. I use yeast nutrient and I have brewed this recipe many times before. It didn't taste right but it has only been a few days. I am still deciding how to proceed so I appreciate the feedback.

1.031 is undrinkable for me. I'd suggest adding additional amylase enzymes to the fermentor. I've had luck doing this to fix a similar situation.

https://www.homebrewtalk.com/thread...ermentation-mountain-ae-to-the-rescue.212926/

 

[littlewashingtonbrewery]

Viscous (as you have described it) sounds like it potetially may be Lactic Acid.

I used viscous as a relative term comparing to the previous bottle of 10% acid I had. I have worked with ink and paint in the past when I had to measure viscosity all the time. I have zahn cups but didn't measure the actual viscosity.

 

[littlewashingtonbrewery]

1.031 is undrinkable for me. I'd suggest adding additional amylase enzymes to the fermentor. I've had luck doing this to fix a similar situation.

https://www.homebrewtalk.com/thread...ermentation-mountain-ae-to-the-rescue.212926/

It is definitely undrinkable right now. Like I said previously, I have brewed this batch many time before. If the 4.2 pH mash reading was correct, which I think it is, I don't think this can be saved. But, I have some amylase enzymes and I will give it a try. Thanks! Nothing to lose.

 

[Silver_Is_Money]

If you have a brix refractometer, take a reading at room temperature. From the Refractometer Brix reading, the weight % phosphoric acid should be:
=1.6027*Bx - 0.001865*Bx^2
where Bx is the Refractometer Brix reading.
At 10%, you should get a reading of about 6.3 Brix.

Above equation should be within +/- 0.1 Wt. Pct.

If you have a refractometer, please post the reading from your sample, and the SG, if you have it.
10% phosphoric acid should have a SG of 1.056 or so. From your picture, I'm going to guess it is much greater than that. Either it isn't phosphoric acid, of they didn't dilute it properly.

Thanks

Nice! Is there a documented source for this?

 

[balrog]

If you have a brix refractometer, take a reading at room temperature. From the Refractometer Brix reading, the weight % phosphoric acid should be:
=1.6027*Bx - 0.001865*Bx^2
where Bx is the Refractometer Brix reading.
At 10%, you should get a reading of about 6.3 Brix.

Above equation should be within +/- 0.1 Wt. Pct.

If you have a refractometer, please post the reading from your sample, and the SG, if you have it.
10% phosphoric acid should have a SG of 1.056 or so. From your picture, I'm going to guess it is much greater than that. Either it isn't phosphoric acid, of they didn't dilute it properly.

Thanks

For my "85% Phosphoric acid"

one drop on refractometer, did not register blue anywhere on the scale. Luckily, neither did I suffer a ship's hull melt-through as in the movie Alien.

I mixed 1ml acid inwith 4ml water (always add acid, admonished my 10th grade chem teacher), and got a reading of 15.4 on the refractometer (I also measure water offset = 0, because).

15.4 means, per @Smiling Frog , 24.24%. If c1v1=c2v2 I should have gotten 17%, which is not that far off given my quick and sloppy ml measuring with two different highly uncalibrated syringes.

 

[Smiling Frog]

Nice! Is there a documented source for this?

Just me. This is merely a empirical 2nd order curve fit to experimental data. If someone could post additional readings they have obtained, it would be helpful to verify my results.

 

[Smiling Frog]

For my "85% Phosphoric acid"
View attachment 727189
one drop on refractometer, did not register blue anywhere on the scale. Luckily, neither did I suffer a ship's hull melt-through as in the movie Alien.
View attachment 727188
I mixed 1ml acid inwith 4ml water (always add acid, admonished my 10th grade chem teacher), and got a reading of 15.4 on the refractometer (I also measure water offset = 0, because).

15.4 means, per @Smiling Frog , 24.24%. If c1v1=c2v2 I should have gotten 17%, which is not that far off given my quick and sloppy ml measuring with two different highly uncalibrated syringes.

I did my dilutions by weight (I have a Mettler electronic scale that has 10mg resolution). I figure measuring mass is easier and more accurate than measuring volumes (particularly since volumes may not be additive). It also makes determining weight percent rather easy.

 

[Silver_Is_Money]

I mixed 1ml acid inwith 4ml water (always add acid, admonished my 10th grade chem teacher), and got a reading of 15.4 on the refractometer (I also measure water offset = 0, because).

15.4 means, per @Smiling Frog , 24.24%. If c1v1=c2v2 I should have gotten 17%, which is not that far off given my quick and sloppy ml measuring with two different highly uncalibrated syringes.

It's not c1v1= c2v2, but rather it is c1v1d1=c2v2d2. The density change from d1 to d2 must not be forgotten.

 

[Smiling Frog]

It's not c1v1= c2v2, but rather it is c1v1d1=c2v2d2. The density change from d1 to d2 must not be forgotten.

So, to put it another way, c1m1=c2m2 where c=concentration (wt. pct.) and m=mass.
Of course, if you're working in percent by volume (or, molarity, if you really want to make things more complicated), things are different.
Definition of terms is important.

 

[littlewashingtonbrewery]

If you have a brix refractometer, take a reading at room temperature. From the Refractometer Brix reading, the weight % phosphoric acid should be:
=1.6027*Bx - 0.001865*Bx^2
where Bx is the Refractometer Brix reading.
At 10%, you should get a reading of about 6.3 Brix.

Above equation should be within +/- 0.1 Wt. Pct.

If you have a refractometer, please post the reading from your sample, and the SG, if you have it.
10% phosphoric acid should have a SG of 1.056 or so. From your picture, I'm going to guess it is much greater than that. Either it isn't phosphoric acid, of they didn't dilute it properly.

Thanks

I tried to measure it with my refractometer and it wouldn't even register. Double checked my refractometer with water, spot on. I measured out 10 mL and it weighed 16.18 gms. I make ammunition and I used a powder scale so I am pretty sure about the accuracy. I still have both my hands. Lol That equals 1.618 gm/ml. Since ml = cm3 my sample is about 1.61 gms/cc. According to Steffen's Chemistry pages 85% solution is 1.689 gm/cc. I didn't adjust for temperature and my graduated cylinder is an Amazon cheapy so I am thinking I have 85% solution.
Am I missing something? Please comment.
Thanks! Really appreciate all the great responses!
Also I double checked the pH of the gravity sample I collected yesterday that stalled at 1.031 and the pH measured 3.71, that is after boiling and hops (4 ounces).

 

[Silver_Is_Money]

So, to put it another way, c1m1=c2m2 where c=concentration (wt. pct.) and m=mass.
Of course, if you're working in percent by volume (or, molarity, if you really want to make things more complicated), things are different.
Definition of terms is important.

Also:
V1M1 = V2M2 (where M = Molarity)

 

[Silver_Is_Money]

I tried to measure it with my refractometer and it wouldn't even register. Double checked with water, spot on. I measured out 10 mL and it weighed 16.16 gms. I make ammunition and I used a powder scale so I am pretty sure about the accuracy. I still have both my hands. Lol That equals 1.61 gm/ml. Since ml = cm3 my sample is about 1.61 gms/cc. According to Steffen's Chemistry pages 85% solution is 1.689 gm/cc. I didn't adjust for temperature and my graduated cylinder is an Amazon cheapy so I am thinking I have 85% solution.
Am I missing something? Please comment.
Thanks! Really appreciate all the great responses!
Also I double checked the pH of the gravity sample I collected yesterday that stalled at 1.031 and the pH measured 3.71, that is after boiling and hops (4 ounces).

Indeed it appears that you are in the density ballpark of 80% Phosphoric Acid (give or take perhaps 5%). If there is a mfg date or lot number on the bottle it might be wise to call the mfgr and let them know. A general recall may be needed here.

 

[balrog]

It's not c1v1= c2v2, but rather it is c1v1d1=c2v2d2. The density change from d1 to d2 must not be forgotten.

I'm not afraid to be schooled, so school me. [Edit: do I just need to weigh the 1ml of acid?]
1 ml of 85% phosphoric, add to 4 ml (consider it distilled) water, total volume 5 ml.
What % should it be?

 

[Smiling Frog]

I tried to measure it with my refractometer and it wouldn't even register. Double checked with water, spot on. I measured out 10 mL and it weighed 16.16 gms. I make ammunition and I used a powder scale so I am pretty sure about the accuracy. I still have both my hands. Lol That equals 1.61 gm/ml. Since ml = cm3 my sample is about 1.61 gms/cc. According to Steffen's Chemistry pages 85% solution is 1.689 gm/cc. I didn't adjust for temperature and my graduated cylinder is an Amazon cheapy so I am thinking I have 85% solution.
Am I missing something? Please comment.
Thanks! Really appreciate all the great responses!
Also I double checked the pH of the gravity sample I collected yesterday that stalled at 1.031 and the pH measured 3.71, that is after boiling and hops (4 ounces).

If I had to guess, I would guess that whoever diluted the phosphoric acid you have did not mix it well. Probably just added the 85% acid to an appropriate volume of water, but did not mix. If filling is done from the bottom, your bottle came from some of the first ones filled. My guess, there are a lot of people out there with a bottle labeled 10% phosphoric acid that is at a considerably lower concentration.

Another possibility is you are not dealing with phosphoric acid at all, but some other liquid, but your pH measurements seem to suggest that it is a concentrated acid and I am not sure what other concentrated acid would approach that density.

ETA: The assumption is that if you had something like sulfuric acid, a hull melt-through would have been evident .

 

[Smiling Frog]

I'm not afraid to be schooled, so school me. [Edit: do I just need to weigh the 1ml of acid?]
1 ml of 85% phosphoric, add to 4 ml (consider it distilled) water, total volume 5 ml.
What % should it be?

0.85 x 1.689 g/ml x 1 ml = 1.435 g phosphoric acid
4 ml water * 0.997 g/ml (density of water at RT) = 3.988 g
1.435 / (1.689 + 3.988) = .2528 or 25.28%

That's pretty close to the 24.24% prediction from the Refractometer Brix reading.

 

[littlewashingtonbrewery]

Indeed it appears that you are in the density ballpark of 80% Phosphoric Acid (give or take perhaps 5%). If there is a mfg date or lot number on the bottle it might be wise to call the mfgr and let them know. A general recall may be needed here.

This is no lot date on the bottle. I called the distributor right after I got the low reading and they said they just repackage what they buy and insisted by email the next day that purchasing did buy the right concentration and that my meter was wrong. I am going to contact them again but I am guessing there might be some upset brewers in the area. They said nobody else called them with this issue. (Yet?? Am I the first?)

 

[Silver_Is_Money]

85% Phosphoric Acid = 14.6502 Molar = 14.6502M

V1M1 = V2M2
1 x 14.6502 = 5 x M2
M2 = 2.93004 Molar Concentration

MW of Phosphoric Acid = 97.995 g/L
Density of specifically 85% Phosphoric Acid = 1.689 g/CC (=~1.689g/mL)

(4 mL x 0.997g/mL) + (1 mL x 1.689g/mL) = 5mL x D2
Ballpark* D2= 1.1372 g/mL density after dilution
(*with the presumption that 4 mL + 1mL = 5 mL, which for blended chemicals is clearly not always the case)

2.93004 Molar = 1000*(Conc x D2)/97.995 g/L
2.93004 = 1000*(Conc x 1.1372)/97.995
287.1293 = 1000*(Conc x 1.1372)
0.287193 = (Conc x 1.1372)
Estimated Concentration =0.2529
Estimated % Concentration = 25.29%

 

[Smiling Frog]

This is no lot date on the bottle. I called the distributor right after I got the low reading and they said they just repackage what they buy and insisted by email the next day that purchasing did buy the right concentration and that my meter was wrong. I am going to contact them again but I am guessing there might be some upset brewers in the area. They said nobody else called them with issue. (Yet?? Am I the first?)

I have noticed high concentrations of phosphoric acid from some distributors before (which is why I created my Brix > Concentration equation). As you are obviously higher than stated, dilute it with distilled water to achieve a Refractometer Brix reading of 6.3 (or a hydrometer reading of 1.056) and save it. They will likely never admit their mistake (think of their liability if every homebrewer wanted them to reimburse them for a couple dozen batches).

ETA: removed reference to supplier. This issue is probably not confined to a specific supplier.

 

[Silver_Is_Money]

Applying c1v1d1=c2v2d2 we get:

85x1x1.689 = c2x5x1.1372
c2=25.25%

 

[Silver_Is_Money]

Differences are likely due to rounding, plus my assumption of 85% Phosphoric Acid being 14.6502 Molar may be a bit off.

Either way, 25.25% and 25.29% are essentially the same value, as is the 25.28% as calculated by @Smiling Frog.

 

[Silver_Is_Money]

Ah, I found my typo error:

2.93004 Molar = 1000*(Conc x D2)/97.995 g/L
2.93004 = 1000*(Conc x 1.1372)/97.995
287.1293 = 1000*(Conc x 1.1372)
0.287193 = (Conc x 1.1372) This should have been entered as 0.2871293
Estimated Concentration =0.2529
Estimated % Concentration = 25.29%

Therefore:
287.1293 = 1000*(Conc x 1.1372)
0.2871293 = (Conc x 1.1372)
Estimated Concentration =0.2525
Estimated % Concentration = 25.25%

 

[Silver_Is_Money]

They said nobody else called them with this issue. (Yet?? Am I the first?)

Not many use pH meters, so it would generally go unnoticed. I'm more worried about someone being seriously burned, or blinded.

That plus a bunch of people ruining batches of beer and having to toss them....