The Dihydrogen Monoxide Parody

     At one time or another just about everybody has seen the dihydrogen monoxide parody on Facebook. It warns us about this substance which is in almost everything we eat and drink is responsible for thousands of deaths annually in the United States alone. 

     The parody often calls for dihydrogen monoxide, or DHMO, to be banned, regulated, or labeled as dangerous. 

     Additionally, it has been observed that DHMO is the major component of acid rain, contributes to the greenhouse effect, can cause severe burns, is fatal if inhaled, contributes to the erosion of the landscape, accelerates corrosion and rusting of many metals, may cause electrical failures and decreased effectiveness of automobile brakes and has been found in excised tumors of terminal cancer patients.

    Despite the danger, dithydrogen monoxide is often used as an industrial solvent and coolant, in nuclear power plants where it is emitted in clouds of vapor, in the production of Styrofoam, as a fire retardant, in many forms of animal research and in pesticides. Even after washing, vegetables that we consume remain contaminated by this chemical. 

     And, we all know some people like one of my Facebook friends who reposts the meme because he believes it is real and he actually wants it banned! This parody plays into chemophobia and demonstrates people's lack of scientific literacy, belief in conspiracy theories, conformation bias and paranoia. Dihydrogen monoxide (DHMO) is a name for the water molecule, H2O. 

     Chemists have developed a description of what liquids are and what they can do, but DHMO breaks the rules. For the purposes of this post DHMO will be referred to by its more common name of water. When in its solid form (ice) and it is dropped into its liquid form the ice floats. Icebergs are another example of the strange phenomenon of a solid floating on its own liquid. Compare that to similar situations. Solid butter won't float on melted butter and rocks won't float on melted rocks (lava).

     Molecules slow down when the get cold and they take up less room. This causes things to shrink a little bit, but ice floats because water expands when it freezes and that makes it a powerful force. Through freezing and melting, water has seeped into rocks and broken them up into soil. 

     In frozen lakes and rivers, the ice insulates the water underneath, keeping it a few degrees above freezing point, even in the coldest of winters. Water is at its most dense at 39.2 degrees F (4 degrees C) and at that temperature it sinks to the bottom of a lake or river. Because bodies of water freeze from the top down, things living in the water have somewhere to survive. If water behaved like a normal liquid this would not be the case. 

     A water molecule is made from two very light atoms (hydrogen and oxygen and, at the ambient conditions on the surface of the Earth it should be a gas.

     Here is a strange fact: hot water freezes faster than cold water; this is known as the Mpemba effect, names after a Tanzanian high-school student named Erasto Mpemba, who found in 1963 that hot ice-cream mix froze faster than a colder mix in a classroom experiment. He wasn't the first to notice this effect though. Other guys like Aristotle, Francis Bacon and Rene Descartes wrote about it, but Erasto gets the credit. 

     Some bugs can walk on and a steel needle can float on the surface of water because of the water’s surface tension, which is immense when compared with that of other liquids. 

     This happens because water molecules stick to each other. In the liquid form, the hydrogen atoms of one water molecule are attracted to the oxygen atom of another molecule. Each water molecule can form up to four bonds and that gives water a cohesiveness unique in liquids. It's this last factor that explains why water is a liquid on the surface of the Earth: the hydrogen bonds hold the molecules together in such a way that more energy than normal is needed to separate them. i.e. to turn water into gas you have to boil it. 

     It's this bonding that enables water molecules to pull each other through the body. Water's ability to dissolve nutrients and and move them around our bodies is important to our life. DNA, proteins and molecules that make up our bodies wouldn’t work without water. The billions of molecules inside our body do their jobs because their interaction with water.

     The same mechanism means that plants can suck water up from deep below the Earth’s surface. 

     Water is difficult to compress because in its natural state its molecules stay closer together than the molecules in other liquids. The harder something is to compress, the easier it is to move it around if you apply a pressure to one side of it. 

     At a mile deep, the ocean’s water is compressed in volume by only about one percent. 

     Water ill stick to almost anything it comes across. Salt (crystals of sodium chloride) dissolves in water because the hydrogen bonds pull the sodium and chlorine atoms away from the crystal, leaving them to float freely through the liquid. 

     Water is so good at dissolving things that it is almost impossible to find it naturally in a pure state; even producing it pure in a laboratory is difficult. Almost every known chemical compound will dissolve in water to a small (but detectable) extent. Because of that, water is one of the most corrosive chemicals known.