pH

who Actually knows what this is and how it works?

Ive been reading crap on the internet lately, that just makes me laugh. Its been so much harder to actually learn what pH is and how it works, after "learning" about pH from reading post after post.

Now, after some formal learning at a schooling institution, i feel like i have an ever so slightly better understanding of it.

I feel like we could all shed some light on this subject.

Anyone care to add some real knowledge and experience. Feel free to.

All pH is, is the measure of the Hydrogen cation concentration "[H+]"
Naturally, with water, H2O splits into H+ and -OH. this makes a fairly even mix b/w both ions (charged things +/-).

at equilibrium, when +=-, its neutral, pH 7. (i wont get into Ka's)

now add an "acid", what are you doing? You are putting something in the solution, that, compared to H2O, more readily gives away its H+ than it picks up another.

now if you put that same "Acid" into something more acid, then it will actually be the base now, and it will accept the stronger acids H+.

Make sense?

its not some chemical that raises and lowers the pH, its H. (or OH for you nerds) now yes, some "chemicals" have more or less H's to give and take. but thats all that is changing. (usually)


It gets Way more complex, but this is a decent knowledge base to build from, so help us all out and contribute your knowledge.
 

Stress_test

I'm always here when I'm not someplace else
Very well stated, I don't believe that I have ever seen it explained quite so simply.
 

Clackamas Coot

Active member
who Actually knows what this is and how it works?

Ive been reading crap on the internet lately, that just makes me laugh. Its been so much harder to actually learn what pH is and how it works, after "learning" about pH from reading post after post.

Now, after some formal learning at a schooling institution, i feel like i have an ever so slightly better understanding of it.

I feel like we could all shed some light on this subject.

Anyone care to add some real knowledge and experience. Feel free to.

All pH is, is the measure of the Hydrogen cation concentration "[H+]"
Naturally, with water, H2O splits into H+ and -OH. this makes a fairly even mix b/w both ions (charged things +/-).

at equilibrium, when +=-, its neutral, pH 7. (i wont get into Ka's)

now add an "acid", what are you doing? You are putting something in the solution, that, compared to H2O, more readily gives away its H+ than it picks up another.

now if you put that same "Acid" into something more acid, then it will actually be the base now, and it will accept the stronger acids H+.

Make sense?

its not some chemical that raises and lowers the pH, its H. (or OH for you nerds) now yes, some "chemicals" have more or less H's to give and take. but thats all that is changing. (usually)


It gets Way more complex, but this is a decent knowledge base to build from, so help us all out and contribute your knowledge.
That's why Calcium (Ca++ which carries 2 'extra' exchange sites), can absorb 2 Hydrogen (H) ions. That's how Ca raises the pH - Cation Exchange Capacity (CeC).

CC
 

bobblehead

Active member
Very nice... Few people actually understand what they're doing when they adjust pH, and why it needs to be in a certain range. Amazing what you can learn in CHEM131, huh? :)

Life is nothing but a series of chemical reactions...
 
from basic chem to organic chem for 2 years, and enviromental chem. you start to make sense of it all some more. plant phys and cell bio and biochem help some too!!


Please explain the Calcium absorbing H to raise pH some more..


Another thing, Humus in soils, humic acids, etc.. they are nothing more than molecules that can bind to soil ions, making them more easily exchanged with the roots. It is my understanding that the pH being out of range, tends to bind more H+ to these sites, thereby, making certain minerals unavailable.

If anything im saying is wrong, please correct me, i want to help others, while helping myself, make sense of this all.


Once you really start to get glimpses of how this miniature world works... its fucking nuts.
 

Clackamas Coot

Active member
f

Please explain the Calcium absorbing H to raise pH some more..

thcrefugee

Once you wrap your brain around most of these concepts you should have a solid base of information about which 'liming agents' should be used - if any.

Here's the lead-in paragraph to give you an idea of the concepts discussed:
"Calcium is present in adequate amounts in most soils. Calcium is a component of several primary and secondary minerals in the soil, which are essentially insoluble for agricultural considerations. These materials are the original sources of the soluble or available forms of Ca. Calcium is also present in relatively soluble forms, as a cation (positively charged Ca++) adsorbed to the soil colloidal complex. The ionic form is considered to be available to crops."
Consider that earthworm castings, as an example, are covered with Calcium Carbonate (CaCO3), all plant-based soil amendments contain high levels of elemental Calcium (Ca++) or those plants would not have been able to grow and develop.

Then you take a look at the molecular structure of dolomite lime and see if using an insoluble form of Magnesium bound to its elemental Calcium component is the best choice (CaMg(CO3) to supplement either Ca or MG. Particularly in the relatively short-term cycles involved in indoor container gardening.

Then review the molecular structure of Calcium Carbonate (CaCO3) which is the form found in limestone, certain oyster shell powders, i.e. 95% Calcaium Carbonate and you can 'generally' take 38% of those numbers to get to the elemental Ca numbers - something like that.

HTH

CC
 
Top