Sulfuric Acid and Water and Coral Snakes

There are coral snakes in South Carolina. There are also non-venomous snakes with the red, yellow, and black colors associated with the potentially-deadly coral snake. If you see a colorful snake, how do you know whether to call 911 if you're bitten? There is a little rhyme:

Red touches yellow can kill a fellow; red touches black, venom lack.

I can't keep the rhyme straight... things like 'red on black, you're a dead man, Jack' run through my head, possibly because one version of the ditty says 'red on black, you're ok Jack'. I did a little reading up on coral snakes before writing this and can share some other helpful facts with you. In the United States, the rhyme holds true: if red and black stripes touch, the snake is non-venomous (or at least much less venomous). However, coral snake color patterns are different in Central America and Africa and it's pretty much a bad plan to mess with any black, yellow, and red snake there. Also, there are mutant snakes, so it's possible to encounter a totally black coral snake or one with pink stripes instead of red stripes. Since I can't remember the rhyme, here's an easier way to tell if you've got a coral snake. Red and yellow are the 'caution and stop' colors of traffic lights. If you see them touching each other on a red/yellow/black snake, leave it alone. Yes, I realize coral snakes are reclusive, tending to come out at night. That's exactly when I am likely to be traipsing barefoot through my yard, so...

How does this relate to sulfuric acid? Whether you add acid to the water or water to the acid is another one of those things I know it's important to remember, but always have to puzzle out. Sulfuric acid (H₂SO₄) reacts very vigorously with water, in a highly exothermic reaction. If you add water to concentrated sulfuric acid, it can boil and spit and you may get a nasty acid burn. If you spill some sulfuric acid on your skin, you want to wash it off with copious amounts of running cold water as soon as possible. Water is less dense than sulfuric acid, so if you pour water on the acid, the reaction occurs on top of the liquid. If you add the acid to the water, it sinks and any wild and crazy reactions have to get through the water or beaker to get to you. How do you remember this? Here are some mnemonics:

• AA - Add Acid
• Acid to Water, like A&W Root Beer
• Always do things as you oughta, add the acid to the water. (um... no... those words don't rhyme in most places.)
• Drop acid, not water. (Don't do that either, ok?)
• If you think your life's too placid, add the water to the acid.

I'm more likely to remember the coral snake rule than any of the sulfuric acid/water mnemonics. I get it right because I figure if I get it wrong, I'd rather have a whole container of water splash on me than a whole container of sulfuric acid, so I take my chances with the small volume of acid and the large volume of water.
Lab Safety Rules | Lab Safety Signs
Photo: Texas Coral Snake (LA Dawson, Austin Reptile Service)