Water

Water is essential for survival and life on earth: It covers more than 70% of the world’s surface and makes up about 60% of our body mass. When two atoms of hydrogen and one molecule of oxygen unite, the result is a molecule of water. Water takes on a few avatars: when room temperature at sea level, fresh water exists as a liquid; at freezing temperatures, it’s a solid; at high temperatures, it transforms into a gas. These states all depend on the arrangement of molecules, how loosely or tightly packed they are. Water is called a universal solvent because more ingredients can dissolve in it than in any other liquid, by far. As a result, it is nearly impossible to find pure water in nature. You can see this for yourself. Take a few drops of tap water and let them dry on a glass surface; depending on the quality of the water, you’ll see a faint to thick residue of a grayish white powder. This powder is made up of the various minerals and salts the water encountered and dissolved along its journey to your faucet.