Firstly, welcome to the blog and I hope you enjoy the first topic - Water.
Water is one of the most common molecules found on earth. So common, in fact, that it covers roughly 70% of it, which adds up to an astounding 330 million cubic miles of it. And yet, despite it being so common and so seemingly simple, at a molecular level it is one of the most complex molecules on the planet. With over 15 different types of ice that we know of and being the only molecule which solid floats on it's own melt, it truly is a fascinating subject. This post will go into what makes water so special, the history of the discovery of the chemistry of water and what we still have yet to find. What is so special about water? Water is very similar to other liquids, but yet has very different properties. Firstly, water is able to hold a lot of energy, more than any other liquid in fact. This also happens to be why boiling water takes so long - It takes a lot more energy to make it change state. In comparison to other molecules, its boiling point is also completely anomalous. On the other end of the spectrum, when water reaches 4 degrees celsius, it does something no other liquid does - it expands. Most liquids lose most of their enery at 4 degrees and contract, making them dense. Water is very different in that ice is actually less dense than water, meaning it can float on its own melt. The molecule water is held together by incredibly strong H-Bonds, which take a lot of energy to break. Shown above is the molecular structure of water. Due to its charges (Oxygen being negative, Hydrogen being positive) there is actually a difference in charges from the bottom of the molecule to the top. At the top, the charge is slightly negative (or delta negative), whereas at the bottom it is positive (delta positive). This structure would also be surrounded by 4 identical molecules, joined together by hydrogen bonds. How was the chemistry of water discovered? Over hundreds of years, the chemistry of water has slowly been taken apart, theories being disproved time and time again. Originally, scientists believed water to be an element on its own, until one day Henry Cavendish discovered hydrogen, after dropping various metals (mainly zinc) into water. However, not understanding what it was, he simply believed it was inflammable air. That was, unitl Lavoisier came along, claiming to have discovered it first and even named it 'Hydrogen'; 'Hydro' meaning water, and 'gen' meaning maker. He also stated that the composition of water was H20, rather than the original theory of just HO. However, this idea of making water wasn't proved until Priestly used an electrostatic machine to spark the air which formed water. Later on, it was Williamson who proves that water was a parent molecule of other molecules, for example, alcohol. What are we still trying to find out about water? How do ions interact with water? Water surrounds ions, but why? Why do ions change the structure of water? Below the boiling point, water molecules are in a disordered arrangement. Why? Each hydrogen atom must be attatched to another hydrogen through hydrogen bonds - Why? When pressure is applied to ice, you either order the hydrogen atoms, aligning the bonds or you rearrange the oxygen arrangement, making them stack in different sequences. Are hydrogen bonds constant? do they flicker on and off?
1 Comment
|
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |