In the watery environment of the body, potassium is highly alkaline-forming...?

Question

..with only 1 valence electron. So when potassium is eaten, how does it cause an increase in OH- . Remeber that KOH in aqueous solution dissolves very quickly, so K bonding to OH then breaking up would have no effect on pH.

Answer 1

The "Potassium" you are talking about is not elemental Potassium (K), it is much more likely to be a Potassium salt of some sort (making it K+).
Potassium metal (K) has the one valence electron you are referring to, but the Potassium ion (K+) has lost that electron already (it has already reacted) and now has a completed octet and is stable.

Potassium, the elemental metal, will explode (or react exceedingly violently) when it comes into contact with water.
2 K + 2 H2O --> H2 + 2 KOH
The heat given off by this reaction ignites the Hydrogen gas which is formed on the products side and the H2 will react with any Oxygen around (in the air) to form water again,
2 H2 + O2 --> 2 H2O
This does not happen inside of a cell for obvious reasons (we don’t explode when we eat bananas).

The "Potassium" referred to in food are really just Potassium containing compounds / salts, they are referring to the Potassium ion, not the metal.

Potassium salts are typically soluble in water and will break into ions. For example, take a general Potassium salt KA (where A is just some general anion with a - charge),
KA --H2O--> K+ (aq) + A- (aq)
This K+ ion in solution will not affect the pH. Depending on what the anion is (A-) in solution, there might or might not be a change in pH....it would depend on the solubility constant for A-.

Answer 2

If one eats metallic postassium (K), very bad things will occur. I wouldn't worry about it, though, since metallic potassium is not naturally found in the metallic state. Eating potassium ion (K+), however is quite safe in the proper amounts and is found in many food sources. Indeed, if all of the potassium ions in your body were removed, you would die.

The reaction you hint at in your question is:

2K + 2H2O --> 2KOH + H2

The result is a net increase in (OH-, from KOH), lowering the pH.

Answer 3

Potassium is a macro nutrient. Its not eaten directly but only in very very minute quantities. At that concentration it does not have an appreciable effect on the body's pH. Its more useful in maintaining the ion balance in the body than the pH.

Or have I misunderstood your question?