Who is Dmitri Mendeleev?
Russian chemist, Dmitri Mendeleev was born in 1834 in a Siberian village. His early life has been described as tumultuous; his father lost his sight and died when Dmitri was thirteen, leaving his family in financial difficulties.
His mother prioritised Dmitiri’s academic potential, taking him and his sister to St Petersburg, where he studied at the Main Pedagogical Institute. When his mother died, he carried out his doctoral research in St Petersburg where he explored the interactions of alcohols with water.
Between 1859 and 1861 he went to Paris to study the densities of gases, and he travelled to Germany where he studied capillarity and surface tension that subsequently led to his theory of ‘absolute boiling point.’ In 1861 he returned to Russia to publish everything he knew on organic chemistry in a 500-page textbook, and by 1864 he became a professor at the Saint Petersburg Technological Institute and Saint Petersburg State University.
As he continued his research, he tried to classify the elements according to the chemical properties. He became aware of a repeating pattern – elements with similar properties appeared at regular intervals. He arranged the elements in order of increasing relative atomic mass and noticed the chemical properties of these elements revealed a trend, which led to the formation of the periodic table.
Beyond his work in chemistry, during the 1870s, he devoted time to help the Russian industry, particularly in strengthening the productivity in agriculture. He became very active in exploring the Russian petroleum industry and developed projects in the coal industry in the Donets Basin. Additionally, he was responsible for creating and introducing the metric system to Russia.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog focuses on Beryllium.
Beryllium copper alloys account for a huge percentage of the beryllium used in the United States. As these alloys are good conductors of electricity and heat, they are used in making connectors, switches and other electrical devices for use in many sectors including aerospace, automobile, computer, defense and medical.
Beryllium metal is very light and stiff and maintains its shape in both high and low temperatures. This makes it the ideal material for use as mirrors of the Spitzer Space Telescope and the James Webb Space Telescope (JWST), due to be launched in the next few years. The key mirror of the JWST comprises 18 hexagonal segments- each must maintain its shape even at - 400 degrees Fahrenheit.
Automobile and Aircraft
Additionally, Beryllium alloy connectors are used in the electrical systems of automobiles, as they are reliable and improve vehicle fuel efficiency.
In commercial aircraft, the strength of beryllium copper provides many advantages, as it can handle wear forces and exposure to corrosive atmospheres and temperatures. Beryllium copper also allows bearings to be made lighter and smaller, which also improves fuel efficiency.
Beryllium copper’s strength and stability makes it ideal for medical technologies and x-ray equipment.
As imaging technology progresses, beryllium copper will continue to play an important role in x-ray tube windows.
Other medical uses of beryllium:
•Springs and membranes for surgical instruments
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry.
Discovery of this noble gas:
In 1894 argon was discovered by chemists Sir William Ramsay and Lord Rayleigh. Ramsay believed the presence of a heavy impurity in the ‘atmospheric’ nitrogen could be responsible for giving nitrogen a higher density when isolated from the air. Both scientists worked to discover this unrecognised new element hiding in the air, winning a Nobel Prize in 1904, primarily for their role in the discovery of argon.
Argon makes up 1% of the earth’s atmosphere and it is the most plentiful of the rare gases. Argon can be both used in its gaseous state and its liquid form. In its liquid state, argon can be stored and transported more easily, affording a cost-effective way to deliver product supply.
Argon as a narcotic agent
One of the most well-known biological effects of argon gas is in its narcotic capabilities. Sea divers normally develop narcotic symptoms under high pressure with normal respiratory air. These symptoms include slowed mental cognition and psychological instability. Argon exerts this narcotic effect in a physical way rather than in a chemical way, as argon, an inert gas, does not undergo chemical reactions in the body.
During the heating and cooling of printing materials, argon provides several benefits to this process. The gas reduces oxidation of the metal preventing reactions and keeping out impurities. This creates a stable printing environment as a constant pressure is maintained.
Future of argon
Argon as a clinical utility tool has received maximum attention. Although the potential benefits are still in the experimental stages, argon could be the ideal neuroprotective agent. Studies have shown that argon could improve cell survival, brain structural integrity and neurological recovery. These protective effects are also efficient when delivered up to 72 hours after brain injury.
Scottish chemist and past SCI President, Sir William Ramsay (1852–1916) came from a long line of scientists on both sides of his family and was described as ‘the greatest chemical discoverer of his time’.
Born in Glasgow, he showed a strong interest in science from a young age and, in his teenage years, he experimented with making fireworks, using materials acquired by his father.
He completed his doctorate in organic chemistry and later, in 1887, was appointed as the Chair of Chemistry at University College London, where he made his most renowned discoveries.
Working with British physicist John William Strutt (better known as Lord Rayleigh), the two men discovered an unknown gas. Owing to its apparent lack of chemical activity, they named the gas argon, meaning “the lazy one”.
After the co-identification of argon, Sir William Ramsay suggested that it be placed into the periodic table between chlorine and potassium in a group with helium. Due to the zero valency of the elements this was named the “zero” group.
From 1895 Ramsay spent three years trying to prove the theory of this new group of gasses, leading to the isolation of helium, neon, krypton and xenon. Eventually, a new column was added to the periodic table.
Ramsay was an outstanding experimentalist. He rolled his own cigarettes, claiming that machine-made ones were unworthy of an experimentalist such as himself.
In 1904, he was awarded the Nobel Prize in Chemistry “for his discovery of the inert gaseous elements in air, and his determination of their place in the Periodic system”. As a result, Ramsay became a considerable celebrity in London and was cartooned both by Spy for Vanity Fair and by Henry Tonks, Head of UCL’s Slade School of Art.
Ramsay ascribed his success in isolating the rare gases to his large flat thumb which could close the end of eudiometer tubes (graduated glass tube used to mix gases) full of mercury.
The group of elements that he discovered is now known commonly as the noble gases and is comprised of helium, neon, argon, krypton, xenon, and radon. Generally, they are chemically inert (they do not react with other elements) this is because they have the desired amount of total s and p electrons in their outermost energy orbital. However, only helium and neon are truly inert. Under very specific conditions, the other noble gases will react on a limited scale.
Today, the noble gasses are in wide use in the real world.
Argon is particularly important for the metal industry, due to the fact that it does not react with the metal at high temperatures. It is used in arc welding (a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal) and is also used in light bulbs to prevent oxygen from corroding the hot filament.
Helium, one of the most common and lightest elements in the universe, is used for diluting the pure oxygen in deep-sea diving tanks. It’s also used to inflate the tires of large aircraft, weather balloons, blimps and party balloons.
Neon, which means ‘New one’ in Greek, is commonly used in colourful glass tube neon signs, it glows bright red when an electric current is sent through the gas, as it enters a plasma state. Other uses of Neon include in vacuum tubes, television tubes, and helium-neon lasers.
Krypton and xenon, valued for their total inertness, are used in photographic flash units, in lightbulbs and in lighthouses, as these elements generate a bright light when an electric current is run through them.
The original glass tubes that Ramsay used to isolate and collect his samples at UCL still exist today, they continue to glow red, yellow, purple and green, more than a century later.
Not only did Ramsay’s successes complete gaps in the periodic table, but he also paved the way for a deeper understanding of how the elements are connected, shaping our understanding today, a huge achievement that can be attributed in no small part to his experimental nature and his large flat thumb!
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the various uses of nitrogen.
Nitrogen – an imperative part of DNA
The polymer that makes up the genetic code of is a sequence of nitrogen bases laid out on a backbone of sugar and phosphate molecules and blended into a double helix.
The nitrogen bases are translated into proteins and enzymes which regulate most our system’s biochemical reactions.
RDX is a nitrogen explosive. This means its explosive properties are primarily caused by the presence of many nitrogen–nitrogen bonds, which are extremely unstable, especially as nitrogen atoms want to come together to produce nitrogen gas due to the triple bond.
Ultimately, the more nitrogen–nitrogen bonds a molecule has, the more explosive it is. RDX is normally combined with other chemicals to make it less sensitive or less likely to explode.
One of the most powerful explosive chemicals is PETN, containing nitro groups and nitroglycerin in dynamite. Despite its powerful explosions, the chemical rarely will detonate alone. PETN was used frequently during World War II, whereby PETN was used to create exploding bridgewire detonators, using electric currents for detonations.
Among the least stable explosives is aziroazide azide, with 14 unstable nitrogen bonds, most of them bonded into unstable nitrogen–nitrogen bonds. Touching or handling this chemical can cause it to detonate, making it one of the most dangerous non-nuclear chemicals.
Nitrogen and plants
Nitrogen plays a significant role for plants to keep healthy. Plants usually contain 3-4% nitrogen in their above-ground tissues. Nitrogen is a major component of chlorophyll which plants use to capture sunlight energy to produce sugars, and a major component of amino acids, which are the building blocks of life.
Overall, nitrogen is a significant component to DNA, a key nutrient to plants, and the uses of nitrogen in everyday life span across various chemical industries including the production of fertilisers and explosives.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today we look at copper and some of its popular uses.
A brief history
Copper was one of the first metals ever extracted and used by humans. According to the US Geological Survey, copper ranks as the third most consumed industrial metal in the world, dating back to around 5000BC.
Around 5500BC, early ancestors discovered the malleable properties of copper, and discovered they could be fashioned into tools and weapons – a discovery that allowed humans to emerge out of the stone age and drift into the age of metals.
Volcanic rocks in Tenerife, Spain.
Approximately two-thirds of the Earth’s copper is found in volcanic rocks, while approximately one-quarter occurs in sedimentary rocks.
Th metal is malleable, meaning it can conduct heat and electricity, making copper an extremely useful industrial metal and is used to make electronics, cables and wiring.
What is it used for?
Since 4500BC humans have made and manufactured items from copper. Copper is used mostly as a pure metal, but its strength and hardness can be adjusted by adding tin to create a copper alloy known as bronze.
In the 1700s, pennies were made from pure copper; in the 1800s they were made from bronze; and today, pennies consist of approximately 97.5% zinc and 2.5% copper.
Copper is utilised for a variety of industrial purposes. In addition to copper’s good thermal and electric conductivity, copper now plays an important role in renewable energy systems.
As copper is an excellent conductor of heat and electricity, power systems use copper to generate and transmit energy with high efficiency and minimal environmental impacts.
E. Coli cultures on a Petri dish.
Copper plays an important role as an anti-bacterial material. Copper alloy surfaces have properties which are set out to destroy a wide range of microorganisms.
Recent studies have shown that copper alloy surfaces kill over 99.9% of E.coli microbes within two hours. In the interest of public health, especially in healthcare environments, studies led by the Environmental Protection Agency (EPA) have listed 274 different copper alloys as certified antimicrobial materials, making copper the first solid surfaced material to have been registered by the EPA.
Copper has always maintained an important role in modern society with a vast list of extensive uses. With further development of renewable energy systems and electric vehicles, we will likely see an ongoing increase in demand for copper.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today we look at arsenic and some of its effects.
What is arsenic?
Arsenic is a chemical element found in nature – low levels of arsenic are found in water, air and soil – in man-made products. As arsenic is distributed throughout the environment, people have high exposure to elevated levels of inorganic arsenic through contaminated drinking water, as well as exposure to arsenic through oceans, food and insecticides.
Is arsenic harmful?
Arsenic can occur in an organic and inorganic form. Organic arsenic compounds are less harmful to our health, whereas, inorganic arsenic compounds (e.g those found in water) are carcinogens, which are highly toxic and dangerous. Arsenic contamination of groundwater has led to arsenic poisoning which affects the skin, liver, lungs and kidneys.
Prominently, arsenic has attracted much attention in Bangladesh, as 21.4% of all the deaths in a highly affected area were caused by levels of arsenic surpassing WHO’s provisional guideline value of 10 μg/L.
Long-term exposure to low doses of arsenic can cause a negative interference in the way cells communicate, which may minimise their ability to function, subsequently playing a role in the development of disease and causing an increase in health risks.
For example, cells use phosphate to communicate with other cells, but arsenate, which is one form of arsenic, can replace and imitate phosphate in the cell. This damages cells so they can not generate energy and impairs the ability of cells to communicate.
The health risks of arsenic in drinking water. Video: EnviroHealthBerkeley
Symptoms of arsenic poisoning can be acute, severe or chronic depending on the period of exposure and method of exposure. Symptoms may include vomiting, abdominal pain and diarrhoea, and long-term exposure can lead to cancers of the bladder and lungs.
Certain industries may face exposure to arsenic’s toxicity, but the maximum exposure to arsenic allowed is limited to 10 micrograms per cubic metre of air for every 8-hour shift. These industries include glass production, smelting, wood treatment, and the use of pesticides. Traces of arsenic can also be found in tobacco, posing a risk to people who smoke cigarettes and other tobacco products.
A global threat
Arsenic is naturally found in the Earth’s crust and can easily contaminate water and food.
WHO has ranked arsenic as one of the top 10 chemicals posing a huge threat to public health. WHO is working to reduce arsenic exposure, however, assessing the dangers on health from arsenic is not straightforward.
As symptoms and signs caused by long-term exposure to inorganic arsenic varies across population groups, geographical regions, as well as between individuals, there is no universal definition of the disease caused by this element. However, continuous efforts and measures are being made to keep concentrations as low as possible.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today we look at mercury and some of its reactions.
Mercury is a silver, heavy, liquid metal. Though mercury is a liquid at room temperature, as a solid it is very soft. Mercury has a variety of uses, mainly in thermometers or as an alloy for tooth fillings.
Mercury & Aluminium
Mercury is added directly to aluminium after the oxide layer is removed. Source: NileRed
The reaction between mercury and aluminium forms an amalgam (alloy of mercury). The aluminium’s oxide layer is disturbed When the amalgam forms, in the following reaction:
Al+ Hg → Al.Hg
Some of the Al.Mg get’s dissolved in the mercury. The aluminium from the amalgam then reacts with the air to form white aluminium oxide fibres, which grow out of the solid metal.
Mercury & Bromine
Mercury and bromine are the only two elements that are liquid at room temperature on the periodic table. Source: Gooferking Science
When mercury and bromine are added together they form mercury(I) bromide in the following reaction:
Hg2 + Br2 → Hg2Br2
This reaction is unique as mercury can form a metal-metal covalent bond, giving mercury(I) bromide a structure of Br-Hg-Hg-Br
Making the Pharaoh's Serpent by igniting mercury (II) thiocyanate. Source: NileRed
The first step of this reaction is to generate water-soluble mercury (II) nitrate by combining mercury and concentrate nitric acid. The reaction goes as follows:
Hg + 4NO3 → Hg(NO3)2 + 2H2O + 2NO2
Next, the reaction is boiled to remove excess NO2 and convert mercury(I) nitrate by-product to mercury (II) nitrate. The mixture is them washed with water and potassium thiocyanate added to the mercury (II) nitrate:
Hg(NO3)2 + 2KSCN→ Hg(SCN)2 + 2KNO3
The mercury (II) thiocyanate appears as a white solid. After this is dried, it can be ignited to produce the Pharaoh’s serpent, as it is converted to mercury sulfide in the following reaction:
Hg(SCN)2 → 2HgS + CS2 + + C3N4
The result is the formation of a snake-like structure. Many of the final products of this process are highly toxic, so although this used to be used as a form of firework, it is no longer commercially available.
Though many reactions of mercury look like a lot of fun, mercury and many of it’s products is highly toxic - so don’t try these at home!
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today we look at helium.
Helium was first discovered by French astronomer Jules Janssen in 1868 when observing the spectral lines of the Sun during a solar eclipse. He initially thought the unidentified line was sodium, later concluding it was an element in the sun unknown to Earth.
In March 1895, Sr William Ramsey, a Scottish chemist, isolated helium on Earth for the first time by treating a mineral called cleveite with mineral acids. He was initially looking for argon, but noticed his spectral lines matched that of Jules Janssen’s.
Helium was discovered when Jules Janssen was observing the solar eclipse spectra.
Helium is a colourless, non-toxic and inert gas. It is the second lightest and second most abundant element in the universe.
Helium is often used for cryogenic (cooling) purposes. Liquid helium has a temperature of -270°C or 4K, which is only 4°C above absolute zero. It is utilised for cooling super conducting magnets.
Helium is used to cool superconducting magnets used in MRI. Image: Pixabay
Super conducting magnets have applications in imaging such as nuclear magnetic resonance (NMR), used for analysing molecules, and magnetic resonance imaging (MRI), a medical imaging device. These techniques are important for scientific research and medical diagnostics.
Helium can also be used a pressurising gas for welding and growing silicon wafer crystals, or as a lifting gas for balloons and airships.
Helium is also used in airships and balloons. Image: Pixabay
A commonly known use of helium is to fill balloons often found at parties and events. When people breathe in the helium gas from these balloons, their voice changes.
As helium is much less dense that nitrogen and oxygen, the two gases that make up regular air, sound travels twice as fast through it. When you speak through helium, the timbre or tone of your voice is affected by this change, causing it to appear higher in pitch.
Why is helium so important? Video: SciShow
Unfortunately, helium is a non-renewable resource, and reserves are running out. There is currently no cheap way to create helium, so industries need to be vigilant when using it, and we may see less helium balloons in the future.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is an element which gives us life, oxygen.
Oxygen is a group 5 gas that is found abundantly in nature. Of the air we breathe, 20.8% is oxygen in its elemental, diatomic form of O2. Oxygen is also one of the most abundant elements in nature, and along with carbon, hydrogen and nitrogen, makes up the structures of most of the natural world. Oxygen can be found in DNA, sugar, hormones, proteins and so many more natural structures.
Although oxygen mainly exists as a colourless gas, at -183°C it can be condensed as a pale blue liquid. Oxygen may seem unsuspecting, but it is highly reactive and highly oxidising. A common example of this reactivity is how oxygen reacts with iron to produce iron oxide, which appears as rust.
Oxygen molecules are paramagnetic – they exhibit magnetic characteristics when in the presence of a magnetic field. Liquid oxygen is so magnetic that the effect can be seen by suspending it between the poles of a powerful magnet.
Oxygen gas has applications for medicine and space travel in breathing apparatus.
Oxygen can be found as ozone or O3. Ozone is a pale blue gas and has a distinctive smell. It is not as stable as diatomic oxygen (dioxygen) and is formed when ultraviolet light (UV) and electrical charges interact with O2.
The highest concentration of ozone can be found in the Earth’s stratosphere, which absorbs the Sun’s UV radiation, providing natural protection for planet Earth.
Ozone (O3) is most concentrated in the stratosphere. Image: Pixabay
Ozone can be used industrially as a powerful oxidising agent. Unfortunately, it can be a dangerous respiratory hazard and pollutant so much be used with care.
Water consists of an oxygen atom and two hydrogen atoms. Though this may seem remarkably unassuming, this combination gives water unique properties that are crucial to it’s functions in the natural world.
Water can form hydrogen bonds between the slightly positive hydrogen and the slightly negative oxygen. These hydrogen bonds, along with waters other practical properties, make water useful in nature.
Without the hydrogen bonding found in water, plants could not transpire – transport water through their phloem’s against gravity. The surface tension of water provides stability for many natural structures.
Oxygen plays a key role in nature, including in water molecules. Image: Pixabay
Oxygen plays a key role in nature, from the ozone layer that encapsulates our planet, to our DNA. It’s combination with hydrogen in water makes a molecule which is integral to the natural world, and both water and oxygen itself are pivotal to our existence the planet.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about iodine and some of the exciting reactions it can do!
Iodine & Aluminium
Reaction between iodine and aluminum. These two components were mixed together, followed by a few drops of hot water. Source: FaceOfChemistry
Reactions between iodine and group 2 metals generally produce a metal iodide. The reaction that occurs is:
2Al(s) + 3I2(s) → Al2I6(s)
Freshly prepared aluminium iodide reacts vigorously with water, particularly if its hot, releasing fumes of hydrogen iodide. The purple colour is given by residual iodine vapours.
Iodine & Zinc
Zinc and iodine react similarly to aluminium and iodine. Source: koen2all
Zinc is another metal, and when it reacts with iodine it too forms a salt – zinc iodide. The reaction is as follows:
Zn + I2→ ZnI2
The reaction is highly exothermic, so we see sublimation of some of the iodide and purple vapours, as with the aluminium reaction. Zinc iodide has uses in industrial radiography and electron microscopy.
Iodine & Sodium
Iodine reacting with molten sodium gives an explosive reaction that resembles fireworks. Source: Bunsen Burns
As with the other two metals, sodium reacts violently with iodine, producing clouds of purple sublimated iodine vapour and sodium iodide. The reaction proceeds as follows:
Na + I2→ 2NaI
Sodium iodide is used as a food supplement and reactant in organic chemistry.
Iodine Clock reaction
The iodine clock reaction – a classic chemical clock used to study kinetics. Source: koen2all
The reaction starts by adding a solution of potassium iodide, sodium thiosuphate and starch to a mixture of hydrogen peroxide and sulphuric acid. A set of two reactions then occur.
First, in a slow reaction, iodine is produced:
H2O2 + 2I− + 2H+ → I2 + 2H2O
This is followed by a second fast reaction, where iodine is converted to iodide by the thiosulphate ion:
2S2O32− + I2 → S4O62− + 2I−
The reaction changes colour to a dark blue or black.
The elephant’s toothpaste reaction is a favourite for chemistry outreach events. Source: koen2all
In this fun reaction, hydrogen peroxide is decomposed into hydrogen and oxygen, and catalysed by potassium iodide. When this reaction is mixed with washing-up liquid, the oxygen and hydrogen gas that is produced creates bubbles and the ‘elephant’s toothpaste’ effect.
There are lot’s of fun reactions to be done with iodine and the other halogens (fluorine, bromine, chlorine).
Iodine’s sublimation to a bright purple vapour makes it’s reactions visually pleasing, and great fun for outreach events and science classes.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about sulphur, specifically sulphites and their significance to the wine industry.
Sulphites and wine - what is all the fuss about? Image: Pixabay
What is a sulphite?
Sulphites are compounds that contain the sulphite ion (sulphate (IV) or SO32- ). There a wide-range of compounds of this type, but common ones include sodium sulphite, potassium bisulphite and sulphur dioxide.
Sulphites are often added as preservatives to a variety of products, and help maintain shelf-life, freshness and taste of the food or drink. They can be found in wines, dried fruits, cold meats and other processed food. Some are produced naturally during wine-making however, they are mainly added in the fermentation process, protecting the wine from bacteria and oxidation.
Sneezing and wine
Sulphites have a bad reputation for causing adverse reactions, such as sneezing and other allergic symptoms. But are sulphites really allergens, or just another urban myth?
Despite it being one of the top nine listed food allergens, many experts believe that the reaction to sulphites in wine can be considered not a ‘true allergy’, rather a sensitivity. Symptoms only usually occur in wine-drinkers with underlying medical issues, such as respiratory problems and asthma, and do not include headaches.
Some people report sneezing and similar symptoms when drinking wine.
Sulphites are considered to be generally safe to eat, unless you test positive in a skin allergy test –some individuals, particularly those who are hyperallergic or aspirin-allergic, may have a true allergy to sulphites. Sufferers of a true allergy would not suffer very mild symptoms if they consumed sulphites, instead they would have to avoid all food with traces of sulphite.
Some scientists believe adverse reactions to red wine could be caused by increased levels of histamine. Fermented products, such as wine and aged cheese, have histamine present, and red wine has significantly more histamine than white wine. They suggest taking an anti-histamine around one hour before drinking to help reduce symptoms.
Despite it not being considered a true allergen, wine-makers must still label wine as containing sulphites. In 1987, a law was passed in the US requiring labels to be placed on wine containing a large amount of added sulphites. Similarly, in 2005, a European law was brought in to regulate European wine labelling. Sulphites are now often listed as a common allergen on bottle labels in wines that have over 10mg/l.
You can often find the words ‘contains sulphites’ on a wine bottle. Image: Pixabay
Many food and drink industries are producing products suitable for allergy sufferers, and winemakers have followed this trend by beginning to make sulphite-free wine. These are mainly dry red wines that contain high levels of tannins, which act as a natural preservative. Wines without added sulphites are generally labelled as organic or natural wines and have grown in popularity over the last few years, but unfortunately, many wine critics believe that these naturally preserved wines sacrifice on flavour and shelf life.
In summary, sulphites are a common preservative, not only found in wine, but a range of food, and do not generally cause allergic reactions. If you are an individual with a true sulphite allergy, you may want to try sulphite free wine – but you will have to compromise on shelf life!
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the highly reactive gas, fluorine.
Fluorine wasn’t discovered until the 19th century, and even now very few chemists have seen elemental fluorine. Fluorite – fluorine’s source mineral – was used industrially as far back as the 16th century, but elemental fluorine wasn’t made until much later.
Fluorite is the mineral form of calcium fluoride (CaF2) and can be found in a wide variety of colours – from pastel free, to burgundy, and even purple or golden yellow. Many samples of fluorite can also be seen fluorescing under UV light. Fluorite’s main industrial use is as a source of hydrogen fluoride (HF), a highly reactive acid. It can also be used to lower the melting point of raw materials, such as steel.
Fluorite has been used in industry for hundreds of years and is fluorescent under UV light. Image: Pixabay
In 1886, French chemist Henri Moissan first made elemental fluorine by electrolysing a mixture of potassium fluoride and hydrogen fluoride. He later won the Nobel Prize in Chemistry for his work.
Large-scale production of fluorine first began during World War II, where it was used to separate uranium for the Manhattan Project – the United States’ nuclear weapons development project.
Fluorine is known for its high reactivity. It is the most electronegative element, which means it can react with almost every other element in the periodic table. Despite being difficult to handle, fluorine and fluorine containing compounds have many real-world applications.
Due to its reactivity, elemental fluorine must be handled with great care. Fluorine reacts with water to produce hydrogen fluoride, which is such a powerful acid it can eat through glassware.
Fluorine’s reactivity isn’t all bad – in fact, it has hundreds of applications. One of the most common uses of fluorine is the fluorides in toothpaste.
These fluorides exist usually as tin or sodium fluoride, and when you brush your teeth they react with calcium in the enamel to make it less soluble to acids. This gives some protection to your teeth from acidic foods such as fizzy drinks or juices.
The fluorochemical industry began in the 1930′s and 40′s with DuPont, who commercialised organofluorine compounds on a large scale. They developed Freon-12 (dichlorodifluoromethane) after General Motors showed chlorofluorcarbons (CFCs) could be used as refrigerants. The two companies joined together to market Freon-12, which quickly replaced previously used toxic kitchen refrigerants.
CFCs were found to be creating holes in the ozone layer, contributing to global warming. Image: Pixabay
CFCs were later banned by a number of countries due to the damage they caused to the ozone layer. More environmentally friendly fluorine-based alternatives are now used in refrigeration, including hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs).
DuPont continued to pioneer the industry, when recently hired chemist Roy J Plunkett accidentally discovered polytetrafluoroethylene, also known as the polymer Teflon. Tests of the mysterious white polymer he had generated showed its’ high temperature stability and resistance against corrosion were significantly higher than any other plastic. It only took three years for large-scale production to begin.
Fluorine – Professor Martyn Poliakoff. Video: Periodic Videos
The development of Teflon lead to many other similar fluorine-containing polymers appearing on the market, including PTFE, which is used in breathable rainwear by the Gore-Tex business and was developed by Robert Gore, the son of ex-DuPont employee Bill Gore.
The fluorochemicals industry continues to grow to this day; in 2017 the global market was estimated at $17.6 billion.