[rparker]

Hello there,
I'm pretty much new to chemistry and really know next to nothing about it. Any help would be welcomed

I'm in the process of manufacturing organic fish fertilizer but need some help with pH levels if anyone is kind enough to help.

Basically I need to lower the pH of 1 litre of liquid fish fertilizer from pH 5.4 to pH 3.0, the acid I'm using is liquid 85% phosphoric acid. How many (ml) of phosphoric acid do I need to lower pH levels?

I need to lower the pH so that the bacteria will stop acting and stop producing gasses. Currently the packaging can't stand the gas pressure and is exploding much to my dismay 

Any help would be great. 

Thanks.

Ryan E. Parker

[Borek]

You don't have enough information to solve the question, as amount of acid depends on the sample composition. Add acid against pH meter till pH is the one you want, that's the best and most sure way of doing it.

[rparker]

Hi there,
Thanks for your reply. Sorry for the lack of information. The fertilizer is mixed with saw dust and molasses and because I have an acute lack of money I can only afford an pH meter that measures purely liquids. At best it is inaccurate because the mixture is an emulsion and isn't an accurate mixture for the pH meter to measure.

Lets just assume the mixture is distilled water with an even pH of 7.0. How much phosphoric acid would I need then? I'll give it a try and see if the fella explodes.

Once again, thank you for you time and effort.

Ryan E. Parker

[kunjal8015]

hello,

you don't have enough inforamtion about the acid
you need the molar concentration of the acid, pretty much how diluted the acid is what we are looking for,
some kind of information about the acid.

[rparker]

Hi there,
Thank you for your reply. On the barrel it says 85% phosphoric acid and it comes from vietnam. If I am not mistaken it is the same type of acid that is used for vehicle bateries. It is liquid and doesn't really sting when it comes to contact with the skin but tastes really sour (yes I did try, I hope nothing bad will happen). With reference to the molar concentration, I don't know what molar means , so I'll give the supplier a call monday, see what they have to say.

Again, thanks for you time and patience.

Ryan E. Parker

[Fridushka]

Is the measure of the concentration of a solute in a solution, or of a molecular, ionic, or atomic species in a given volume..
Molar concentration (Cx) or molarity (M):
nsolute/Vsoln = [no. (m)mol solute / no. (m)L soln]

[kunjal8015]

ok so it says it's 85% phosphoric acid on a barrel what's the volume of barrel.

pretty much this means that 85% of the barrel is phosphoric acid and rest is water or other solution user for dilution.

[kunjal8015]

if they have formula for phosphoric acid please provide, but that's OK if they don't.

[Fridushka]

I'm not that advanced in chemistry because I'll start my 2^nd year..well there will be no need for another formula because it a general thing, and throughout my experience haven't used sothing else, although i don't know if there is, I'm not that sure!

[rparker]

Thank you so much for your interest,
The barrel is 35kg (I weighed it myself).

Thanks you.

Ryan E. Parker

[Borek]

If I am not mistaken it is the same type of acid that is used for vehicle bateries.

No, vehicle batteries use sulfuric acid, not phosphoric.

Even assuming you start with pH 7.0 solution won't help. Your fertilizer for sure contains substances that will work as buffers, that is, they will prevent pH changes. Not knowing their amounts you can as well use your shoe number as a volume of the acid that has to be added.

[rparker]

Lets just assume its it is distilled water, how many ml phosphoric acid at 85% concentration to to bring pH 5.4 to ph 3.0 for the 1 litre of distilled water. I really just need a number to start with to get things going. I'll work backwards from that.

Thanks.

Ryan E. Parker

[nj_bartel]

Just for future reference... tasting acids and chemicals in general... not generally very smart.

[Borek]

Lets just assume its it is distilled water, how many ml phosphoric acid at 85% concentration to to bring pH 5.4 to ph 3.0 for the 1 litre of distilled water. I really just need a number to start with to get things going. I'll work backwards from that.

0.001M solution of phosphoric acid have pH 3.0, that means around 0.06 mL added to 1 liter of distilled water.

This is not true, as I have no idea why the water had pH 5.4 in the first place, then it is very likely that when you add that amount of acid to your solution (you may assume it is a single, small drop) pH will change by less than 0.1 unit, depending on the composition. So in fact you still know nothing.

If you can't afford pH meter, buy pH strips.