Sodium Hydroxide

[JGT]

So I was refilling my 5 gal jug of sodium hydroxide and came upstairs and showed my wife a few of the burns it gave me on my leg and arm. Normal occurrence. Despite me wearing gloves and being super careful some always splashes and gets me. And she asked me how come it doesn’t hurt or burn the fish. I was like I’m not sure. Probably because it gets so diluted when it enters the tank but figured I’d get an answer or confirmation here.

 

[Johnd651]

Yep, dilution is the solution...( and it goes on, but that's all we need here.)

M1V1=M2V2, so when in its initial solution, the concentration of NaOH is high, but as you increase volume 2, your molarity (concentration) goes down.

 

[Randy Holmes-Farley Verified Community Expert]

sorry to hear what happened. Be certain to protect yourself, especially your eyes.

The pH of a typical dosing solution is above 14. At that pH, the hydroxide reacts with fats in your skin, converting them to fatty acids. That disrupts membranes and damages cells. Other things happen too, but that’s the one that causes the slippery feel. That reaction is the old way of making soap: fat + lye —> soap + glycerol.

Once in the tank water, the pH is below 9, both from dilution and by reaction with bicarbonate to reduce the hydroxide even more, forming carbonate. That pH change has lowered the hydroxide concentration by a factor of several hundred thousand. The same reaction likely still proceeds to make fatty acids, but several hundred times slower so that it is not noticed.

All of the other effects of hydroxide are also greatly reduced as well, and you don’t get the same sort of cell damage putting your hand in seawater.

 

[JGT]

sorry to hear what happened. Be certain to protect yourself, especially your eyes.

The pH of a typical dosing solution is above 14. At that pH, the hydroxide reacts with fats in your skin, converting them to fatty acids. That disrupts membranes and damages cells. Other things happen too, but that’s the one that causes the slippery feel. That reaction is the old way of making soap: fat + lye —> soap + glycerol.

Once in the tank water, the pH is below 9, both from dilution and by reaction with bicarbonate to reduce the hydroxide even more, forming carbonate. That pH change has lowered the hydroxide concentration by a factor of several hundred thousand. The same reaction likely still proceeds to make fatty acids, but several hundred times slower so that it is not noticed.

All of the other effects of hydroxide are also greatly reduced as well, and you don’t get the same sort of cell damage putting your hand in seawater.

Thanks. Yes, I am careful but one of the casualties of the hobby. Always seems to somehow get a few drops on exposed skin. I can see how mobsters use this stuff to dissolve their victims in a barrel. Great for alk and PH though.