What are some interesting facts about chemistry?

Chemistry is a fascinating science full of unusual trivia. A list of some of the most fun and most interesting chemistry facts.

• The only solid elements that assume liquid form ​at room temperature are bromine and mercury. However, you can melt gallium by holding a lump in the warmth of your hand.

• Unlike many substances, water expands as it freezes. An ice cube takes up about 9% more volume than the water used to make it.
• If you pour a handful of salt into a full glass of water, the water level will actually go down rather than overflowing the glass.
• Similarly, if you mix half a liter of alcohol and half a liter of water, the total volume of the liquid will be less than one liter.
• There is about 1/2 lb or 250 g of salt (NaCl) in the average adult human body.
• A pure element takes many forms. For example, diamond and graphite both are forms of pure carbon.
• Many radioactive elements actually glow in the dark.
• The chemical name for water (H2O) is dihydrogen monoxide.
• The only letter not appearing on the periodic table is J.
• Lightning strikes produce O3, which is ozone, and strengthen the ozone layer of the atmosphere.
• The only two non-silvery metals are gold and copper.
• Although oxygen gas is colorless, the liquid and solid forms of oxygen are blue.
• The human body contains enough carbon to provide 'lead' (which is really graphite) for about 9,000 pencils.
• Hydrogen is the most abundant element in the universe, while oxygen is the most abundant element in the earth's atmosphere, crust, and oceans (about 49.5%).
• The rarest naturally-occurring element in the earth's crust may be astatine. The entire crust appears to contain about 28 g of the element.
• Hydrofluoric acid is so corrosive that it will dissolve glass. Although it is corrosive, hydrofluoric acid is considered to be a 'weak acid'.
• One bucket full of water contains more atoms than there are buckets of water in the Atlantic ocean.
• Approximately 20% of the oxygen in the atmosphere was produced by the Amazon rainforest.
• Helium balloons float because helium is lighter than air.
• Bee stings are acidic while wasp stings are alkaline.
• Hot peppers get their heat from a molecule called capsaicin. While the molecule acts as an irritant to mammals, including humans, birds lack the receptor responsible for the effect and are immune to the burning sensation from exposure.
• It's possible to die from drinking too much water.
• Dry ice is the solid form of carbon dioxide (CO2).
• Liquid air has a bluish tint, similar to water.
• You can't freeze helium simply by cooling it to absolute zero. It will freeze if you apply extremely intense pressure.
• By the time you feel thirsty, you've already lost about 1% of your body's water.
• Mars is red because its surface contains a lot of iron oxide or rust.
• Sometimes hot water freezes more quickly than cold water. A high school student documented the effect, which bears his name (the Mpemba effect).

What is the difference between Chemistry and Green Chemistry?

Chemistry is the study of matter, the way matter (atoms and molecules and compounds) interacts to give rise to a whole range of processes. It is also the study of the behavior of individual atoms, molecules and compounds. Chemistry is also known as the “central science” because the study of Chemistry is also important for Physics and Biology. Chemistry is, basically, the study of all the different types of atoms, molecules, compounds and the processes and phenomena that happen when they interact.

Green Chemistry is a specific field of Chemistry involving the study of atoms, molecules, compounds and determining whether the usage of such matter is safe for the environment.

DIFFERENCES:

1. Chemistry is a very broad science, meaning that it covers a large range of theories, whereas, Green Chemistry is only a fraction of Chemistry.
2. Chemistry aims at developing chemicals for the welfare of the humans, whereas Green Chemistry aims at developing chemicals for the welfare of the humans but in the same time, not adversely affecting the environment.

What is the difference between polymer science, polymer chemistry, and polymer physics?

Polymer Science is a generic term covering the various subdivisions of the subject.
 Polymer chemists are mostly interested in the task of making plastic substances from their precursor chemicals; by reacting ethylene, propene or other hydrocarbons with catalysts under appropriate conditions Eg high pressure. Plastics or thermoplastics are typically made by free radical chain reactions. 
In contrast polymer resins or thermosets, another class of man made polymers, are made by cross linking various reactive momomers or oligomers together, Eg polyurethane paint when spread into a thin film eg on a wall, undergoes a cross linking reaction to form a resin; the crosslinking reaction is induced by atmospheric oxygen. Resins unlike plastics are essentially one big molecule ! 

That's why there are few if any solvents for them. In contrast plastics can be softened with solvents being linear in their structure at the molecular level. 
The distribution of polymer chain lengths in a given plastic material is largely controlled by the kinetics of the free radical chain reaction, in the monomer to polymer conversion process. So you've got to like reaction kinetics if you want to be a polymer chemist !  Lots of physical chemistry. 
Rubbers are amorphous thermoplastics above their glass transition temperature. Polymer spectroscopy carried out for polymer material identification purposes is also a speciality within the field of polymer chemistry. Also gel permeation chromatography or gpc which is another polymer characterization technique. 
 
Polymer blending is another subject within polymer materials science. Also thermal analysis, using techniques such as TG, DTA, & DSC. 

Turning to polymer engineering. Polymer engineers often have degrees in mechanical engineering. Polymer engineering concerns itself with the moulding or castings of polymer materials into useful engineering products. Things such as plastic buckets, rainwater goods, tyres, yacht hulls, plastic bottles, aircraft windows,  plastic shopping bags, sneakers, shoes, car panels, train seats, aircraft interiors, vending machine tea cups, toys, sports equipment etc, the list goes on !


Polymer technology has a slightly broader remit covering subjects in addition to polymer engineering ranging from polymer additives for car engine oil ( Eg star polymers ), to medical polymers (Eg pace makers ), polymers in electronics, household paints, fabrics, rope, polythene beakers for hydrofluoric acid. In fact any useful application.

What are the different research fields in Inorganic Chemistry?

Research fields in Inorganic Chemistry are as wide as Inorganic Chemistry itself. Everything you read about in Chemistry textbooks were discovered at one time or another.
So research in Inorganic Chemistry will cover the chemistry & some of the physical properties of each of the individual elements in the periodic table and their compounds, apart from the organic chemistry of carbon.
A major discovery in Inorganic Chemistry could be something like the first example of the compound of an element having a new oxidation state. Or the first example of a compound of the element Neon. No known compounds of Neon exist. It is the least reactive element in The Periodic Table. So a major discovery like that would be accepted for publication in a major international scientific journals. Eg. Nature. A discovery like that may make it to the TV news as a story stating that for the first time in history all known elements are now known to form chemical compounds.

Here are a few research areas :

• Main group reaction chemistry
• Inorganic vibrational spectroscopy
• Transition metal chemistry
• Magnetochemistry
• Theoretical inorganic chemistry
• Non-aqueous solvent chemistry
• High temperature chemistry
• Fused salt chemistry
• Solid state chemistry
• Battery technology
• Nuclear chemistry
• Trans-Uranium chemistry
• Lanthanides and Actinides
• Organometallic chemistry
• Heterogeneous catalysis
• Homogeneous catalysis
• Materials chemistry
• Glass science
• Organoboranes
• Cryptands
• X-ray crystallography
• Electronic spectroscopy in inorganic chemistry
• Matrix isolation and low temperature chemistry
• Energetic materials

What is the use of food chemistry in food tech?

If you are a food technologist and still you are asking this question then you must question your knowledge.

And if not then read the following explanation:

Food technology is the field in which one deals with processing and preservation of food. One also reads about different processing techniques and technologies. Any technology will get acceptance only if it solves some need and also has minimum side effects. Taking this point in mind one can really understand the role of food chemistry in food technology.

Firstly, food chemistry helps one understand the basic structure and properties in components of foods e.g the carbohydrate fats and proteins. Upon understanding the chemistry of the components of food one can really understand the impact a processing technique is going to have on the food. Let us take example of heat processing techniques like pasteurization. In this case the extent of the treatment will be depending on extent of adverse effects that can be allowed on these components. So from where do we get the idea of these adverse effects. The answer is food chemistry which gives us useful insights into mailard reaction, denaturation of proteins and oxidation of fats. And the use of food chemistry is not just limited to above examples but also includes the vitamins, food pigments and antioxidants.

So, basically this is how useful, food chemistry is in food technology.

What are R groups in organic chemistry?

R group in Organic chemistry refers to the alkyl group which may be either straight chain ( like -CH3, -C2H5,etc) or branched [ isopropyl -CH(CH3)2 or neobutyl -C(CH3)3,etc]. This alkyl group is due to the substitution of a hydrogen atom of alkane ( from alkane to alkyl) with any other functional group. 
Even aromatic compounds do contain alkyl group. Just a simple example if we remove a hydrogen atom from benzene (C6H6) we get a phenyl group which is an alkyl group (-C6H5) therefore in chlorobenzene, phenyl is the R part.

For example if you look at this reaction:

only the top left OH group is reacting so a simplified version would be

for example if you look at this reaction

only the top left OH group is reacting so a simplified version would be

What is the meaning of charge transfer resistance in electrochemistry?

Charge transfer resistance has to do with the process of electron transfer from one phase (e.g. electrode) to another (e.g. liquid). Take, for example, the electrolysis of water. On the cathode hydrogen is reduced to H2 gas. 

It takes energy to remove electrons from a metal electrode and join them with the protons to produce hydrogen. Thus, the process of transferring electrons from the electrode to the hydrogen ions in the liquid phase has a certain resistance associated with it and this resistance can be given in ohms just like regular ohmic resistance. That resistance is charge transfer resistance.