I’m fascinated by applying my education to solve real-life problems. My favorite moments last quarter in the second installment of general chemistry were when we used the chemistry we learned in class to better understand the world. Because I’m still excited by this particular connection (not because of the content, though; the situation that caused this is devastating), I wanted to share my knowledge. Please keep in mind this information is coming from a first-year chemistry course and that I am attempting to communicate the science to everyone, regardless of chemistry background. Here goes!

Throughout the duration of this explanation, it would be helpful to visualize mosquitoes attracted to a light. Imagine a bright light-bulb on a porch at a muggy 88° F. Lots of mosquitoes are attracted to this bulb. In fact, the mosquitoes are so attracted to this bulb that they’re already surrounding the bulb. Now, every now and then a few mosquitoes fall off, but after they fall, they charge back at the light because they prefer to be attached to the light. As soon as they charge back in, however, a few different mosquitoes fall off. This goes on indefinitely at this temperature, with mosquitoes exchanging back and forth. Though the forward reaction of mosquitoes falling off the bulb happens (bulb to air), mosquitoes prefer being attached to the bulb, and therefore most mosquitoes favor the reverse reaction (air to bulb) where they are attached to the light-bulb.

Lead pipes are commonly used in urban water distribution systems because of lead’s ability to resist leaking while still being malleable and easy to shape into pipes. Lead compounds, though largely considered insoluble (i.e. materials that do not dissolve in water), do still have solubility constants, and higher solubility constants translate into more soluble compounds (more of the compound dissolves in water). Lead compounds that make up lead piping often have very, very small solubility constants (10^-20, for example, which means that about 0.00000000000000000001 moles of compound dissolve per 1 L of water, where one mole are 6.022 x 10²³ molecules; in other words, a really tiny amount!). This is similar to the mosquitoes falling off the bulb; even though the mosquitoes greatly prefer to be attached to the light-bulb, they still fall off.

The reaction where lead compounds dissolve is reversible, and because the solubility constant is so small in the forward direction where the compound dissolves, the reverse reaction is favored, meaning that lead compounds prefer to remain intact and dissolved ions will reform solid compound. Even when lead dissolves a little bit, the little bit that dissolves will often return to the solid compound form. This is like when the mosquitoes rejoin the light-bulb; this “reverse reaction” of mosquitoes reattaching themselves to the bulb is favored, and hence more mosquitoes will be attached to the bulb than will be buzzing around in the air surrounding the light-bulb. It is important to note that solubility constants are temperature dependent, meaning that as temperature changes the solubility constant does as well.

Now, say that a heavy burlap sack is tightly wrapped around the mosquito-bulb complex (without squishing the mosquitoes, of course). Very few, if any, mosquitoes will be able to penetrate through the burlap sack. Hence, the air remains mosquito-free (assuming the only mosquitoes in the world are attached to the light-bulb), because if the mosquitoes can’t break away from the light-bulb and are not in contact with the air, they cannot buzz around freely. Our goal is to keep mosquitoes out of the air so they don’t bite us, and the burlap sack helps us achieve that goal.

Mineralizing layers are the burlap sack equivalent in lead pipes; they separate the lead compounds that make up lead pipes from the water in which they could dissolve. Adding phosphate salts to water prevents metal contamination by continually reinforcing the mineralizing layer, which in turn prevents lead ions from dissolving.

Now, imagine if the burlap sack that’s encasing the materials began to thin and wear down because clumps of hail begin banging into it; eventually, more and more mosquitoes would be able to escape. When Flint, MI switched water sources to a highly corrosive river with hard metals (presumably to save money), anti-corrosive phosphate salts were not added to the water supply. As a result, the hard metals in the water supply broke down the mineralizing layer, and lead ions were able to dissolve in the water. It is important to note that lead dissolving in small amounts still leads to clear, colorless water. In Flint, MI, however, the water flowing out of pipes was brown, meaning that a significant amount of lead dissolved into the water supply; this is likely due to corrosion that caused even more lead to dissolve. Lead is toxic to humans; it accumulates in our bodies and has negative health effects, especially on children (examples include stunting brain and central nervous system growth, high blood pressure and kidney damage).

After a series of mismanaged warnings that could have lead to earlier detection, Michigan Governor Rick Snyder and President Barack Obama declared that Flint was in a state of emergency. The city switched back to its original non-corrosive water supply, but lingering lead means the water is still unsafe to drink. Some scientists propose, in addition to fixing damaged pipes, to allow the mineralizing layer to rebuild on its own in order to fix the supply (because remember, the reverse reaction of solid lead compounds is favored), though it is unclear how long it will take for the pipe’s “burlap sack” to reform.

For now, the residents of Flint, MI are surviving on bottled water and filter systems. It is distressing to know that preventable negligence from switching water sources will have long-term effects on so many people – especially children – in Flint, and I hope that the damages can somehow be repaired. CNN offers suggestions for how we can help with the water crisis.