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Did you know that the solubility of oxygen in water is inversely proportional to temperature? That means that the colder the water is, the more dissolved oxygen it contains. But then if you try to dissolve salt in freshwater you’ll find that the hotter the water is, the more salt you can mix into the solution. So what gives? Why does a gas dissolve more easily in cold water while a solid dissolves more easily in hot water? A great explanation came from Henry Louis Le Châtelier, a French chemist who developed the “Equilibrium Law” also known as Le Châtelier’s principle. He discovered that a system will counteract a disturbance in its equilibrium. Because dissolving oxygen in water is an exothermic process, a drop in temperature of the water (energy removed from the system) is balanced by more oxygen dissolving into the water, which releases energy to counterbalance what was removed. Dissolving salt into water is an endothermic process, meaning that the opposite balance of equilibrium occurs. This balance between water, oxygen, and salt is extremely important to the health of our oceans. In parts of the world where water is extremely warm, the water can absorb lots of salt and very little oxygen. This can create what are called hypoxic or “dead zones”. Here the oxygen content in the water is so low and the salt content so high that life cannot survive.