P&R Labpak - Everything for your laboratory

P&R Labpak - Everything for your laboratory
Our Head Office in St Helens

Friday, 19 December 2014

Christmas Closure

P&R Labpak closes on Wednesday 24th December 2014 and re-opens on 5th January 2015. There will be no deliveries during this period.

P&R Labpak would like to take this opportunity now to thank you for your custom this year, and look forward to continuing our relationships in 2015.

We hope you've enjoyed our blog posts over the last year and hope you will continue to read them in future.  If you want us to feature anything or try and answer a question for you then let us know.

Remember to LIKE us on Facebook and subscribe to our Twitter feed too!

Friday, 12 December 2014

Glow Sticks!

A glow stick is a self-contained, short-term light-source. It consists of a translucent plastic tube containing isolated substances that, when combined, make light through chemiluminescence, so it does not require an external energy source. The light cannot be turned off, and can be used only once. Glow sticks are often used for recreation, but may also be relied upon for light during military, police, fire, or Emergency operations.

Chemistry of Glow Stick Colours
A glow stick contains two chemicals and a suitable dye. The chemicals inside the plastic tube are a mixture of the dye and diphenyl oxalate. The chemical in the glass vial is hydrogen peroxide. By mixing the peroxide with the phenyl oxalate ester, a chemical reaction takes place, yielding two molecules of phenol and one molecule of peroxyacid ester (1,2-dioxetanedione). The peroxyacid decomposes spontaneously to carbon dioxide, releasing energy that excites the dye, which then relaxes by releasing a photon. The wavelength of the photon—the color of the emitted light—depends on the structure of the dye.

As stated by the excellent article by Compound Interest, a range of different chemicals can be used, including those shown above, as well as one or two additional dyes. Whilst the molecules of the dye are always present in the solution, the hydrogen peroxide and the diphenyl oxalate are slowly used up by the reaction, until one runs out and the reaction ceases – and it’s at this point that the glow stick will stop emitting its glow.

Friday, 5 December 2014

Christmas Tree Needle Drop

It's that time of year when we think about whether to get a 'real' Christmas tree or whether to get the artificial one out of the loft to decorate.

One of the problems of real trees is needle drop.  First you have to decorate the tree without getting too many injuries from the sharp needles.  Then you have to face the task of collecting the fallen needles on the carpet as the tree slowly withers.

Scientists have looked into the problem of needle drop.

Researchers identified a plant hormone, ethylene responsible for needle loss in balsam fir. They made the discovery by placing fir branches in containers of water inside a growth chamber. After ten days the branches began to produce ethylene and three days later the needles began to drop. After 40 days, the branches were completely bare.

To test that the needle loss was in fact due to the ethylene, the researchers used two chemical compounds that interfere with this hormone: 1-MCP and AVG. After exposing the branches to one of these two products, the needle retention period rose to 73 and 87 days, respectively.

It should be possible to dissolve AVG in the water added to the tree stand, which would prolong the tree's lifespan indoors.  Any Ethylene inhibitors should work.

There are other ways to prolong the life of your tree.

Choose your tree carefully.  Norway spruce (traditional choice but with a quick needle drop rate); Nordmann fir (dark green and expensive but also boasts of a slow needle drop); Noble fir (the king of Christmas trees and again holds a better track record of needle drop than the Norway spruce); Fraser fir (excellent needle-holding properties and a lovely pine fragrance to boot and resembles the Norway spruce).

Make a new cut on the stump when you first buy it or get it home, at least an inch above the previous cut. Put the tree in water immediately, and maintain the water level. Keep temperatures in your home slightly cooler, if possible, and position the tree away from the kitchen. Also, keep fruits away from the tree as they give off ethylene. Lastly, leave the lights on at night. Being left in the dark causes a tree to respire more, using up its carbohydrates. As a result, says Dr. Raj Lada of the Christmas Tree Research Center, "it can be starved to death."

Above all else - decorate and enjoy - don't eat all the chocolates on the tree before Christmas!

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Friday, 28 November 2014

The livestream below is from one of the four commercial, off-the-shelf high-definition cameras, which take turns streaming a live video feed of Earth for online viewing.

As NASA says, "The cameras are enclosed in a temperature specific housing and are exposed to the harsh radiation of space."

"Analysis of the effect of space on the video quality, over the time HDEV is operational, may help engineers decide which cameras are the best types to use on future missions."

The system is operated one camera at a time on an automated repeating cycle so that the video follows a location on Earth as the ISS passes over, all with no intervention from human operators. It also drops out relatively frequently due to loss of Ku-band transmission, and it goes completely dark while in the night sections.

It's fascinating to watch and is strangely relaxing.  Enjoy!

Broadcast live streaming video on Ustream

Black Scenes = Night side of the Earth

The live video feed from HDEV will occasionally be unavailable due to loss of Ku-band transmission from the International Space Station. Please check the site again in approximately 30 minutes

Friday, 21 November 2014


An analgesic, or painkiller, is any member of the group of drugs used to achieve analgesia — relief from pain. The word analgesic derives from Greek ἀν-, "without", and ἄλγος, "pain.

There are two main types of painkiller - opioids and non-steroid anti-inflammatory drugs (or NSAIDs).  The type of medicines that you need to treat your pain depend on what type of pain you have.


Analgesic drugs act in various ways on the peripheral and central nervous systems. They are distinct from anesthetics, which reversibly eliminate sensation, and include paracetamol (known in the US as acetaminophen or simply APAP), the non-steroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, and opioid drugs such as morphine and oxycodone.

The exact mechanism of action of paracetamol/acetaminophen is uncertain but appears to act centrally in the brain rather than peripherally in nerve endings. Aspirin and the other non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases, leading to a decrease in prostaglandin production. In contrast to paracetamol and the opioids, this reduces not only pain but inflammation as well.
The graphic below from Compound Interest takes a look at a selection of common painkillers, their common brand names, and how they work.

Click to enlarge

For pain associated with inflammation, such as back pain or headaches, paracetamol and anti-inflammatory painkillers work best.

If the pain is caused by sensitive or damaged nerves, as is the case with shingles or sciatica, it is usually treated with tablets that are also used for epilepsy and depression. These tablets change the way the central nervous system works.

The aim of taking medication is to improve your quality of life. All painkillers have potential side effects, so you need to weigh up the advantages of taking them against the disadvantages

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Friday, 14 November 2014


Platinum has the chemical symbol Pt and atomic number 78. It’s a dense, malleable, ductile, highly unreactive, precious, grey-white transition metal. Its name is derived from the Spanish term platina, which is literally translated into "little silver”.

Platinum occurs in the wild as the pure element as well as alloyed with iridium, known as platiniridium.  It is one of the rarest elements in the Earth's crust with an average abundance of approximately 5 μg/kg.

In addition to its high density, resistance to oxidation and other desirable qualities, platinum is remarkably chemically unreactive. For these reasons, a 90-10% alloy of platinum-iridium is still used as the International Prototype Kilogram. Originally, this prototype kilogram was made of pure platinum, but iridium was added to increase its hardness while retaining platinum's many desirable qualities.

Platinum Nuggets

Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewellery. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals. Some compounds containing platinum are applied in chemotherapy against certain types of cancer.

Platinum;s resistance to wear and tarnish is well suited to its use in fine jewellery.

Platinum is obtained commercially as a by-product from nickel and copper mining and processing.  As an example, of the 245 tonnes of platinum sold in 2010, 113 tonnes were used for vehicle emissions control devices (46%), 76 tonnes for jewellery (31%). The remaining 35.5 tonnes went to various other minor applications, such as investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.

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Friday, 7 November 2014

On this day - Marie Curie

Marie Curie was a Polish-born physicist and chemist and one of the most famous scientists of her time. Together with her husband Pierre, she was awarded the Nobel Prize in 1903, and she went on to win another in 1911.

Marie Sklodowska was born in Warsaw on 7 November 1867, the daughter of a teacher. In 1891, she went to Paris to study physics and mathematics at the Sorbonne where she met Pierre Curie, professor of the School of Physics. They were married in 1895.

She developed a theory of radioactivity (a term that she coined) and techniques for isolating radioactive isotopes.  She also discovered two elements, polonium and radium. Under her direction, the world's first studies were conducted into the treatment of neoplasms, using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today.
During World War I, she established the first military field radiological centres.  After a quick study of radiology, anatomy, and automotive mechanics she procured X-ray equipment, vehicles, auxiliary generators, and developed mobile radiography units, which came to be popularly known as petites Curies ("Little Curies").  She became the director of the Red Cross Radiology Service and set up France's first military radiology centre, operational by late 1914.
Marie and her husband worked together investigating radioactivity, building on the work of the German physicist Roentgen and the French physicist Becquerel. In July 1898, the Curies announced the discovery of a new chemical element, polonium. At the end of the year, they announced the discovery of another, radium. The Curies, along with Becquerel, were awarded the Nobel Prize for Physics in 1903.

Marie received a second Nobel Prize, for Chemistry, in 1911.

Curie died in 1934 due to aplastic anaemia brought on by exposure to radiation – including carrying test tubes of radium in her pockets during research (she also stored them in her desk drawer, remarking on the faint light that the substances gave off in the dark) and her World War I service in mobile X-ray units created by her.  She was exposed to X-rays from unshielded equipment.

Marie and Pierre Curie experimenting with radium, a drawing by André Castaigne

Because of their levels of radioactivity, her papers from the 1890s are considered too dangerous to handle.  Even her cookbook is highly radioactive.  Her papers are kept in lead-lined boxes, and those who wish to consult them must wear protective clothing.

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Friday, 31 October 2014

Autumn leaves - the chemistry behind the colour

As Autumn pushes onwards the leaves on the trees have lost their green colour and have allowed the vibrant hues of autumn to show through. Although this change may initially seem a simple one, the vivid colours are a result of a range of chemical compounds.

A green leaf is green because of the presence of a pigment known as chlorophyll, which is inside an organelle called a chloroplast. When they are abundant in the leaf's cells, as they are during the growing season, the chlorophylls' green colour dominates and masks out the colours of any other pigments that may be present in the leaf. Thus the leaves of summer are characteristically green.

As summer fades, so too does the amount of light, and thus chlorophyll production slows  The existing chlorophyll decomposes. As a result of this, other compounds present in the leaves can come to the fore, and affect the perceived colouration as shown in the infographic below featured on the CompoundInterest website.  Click on the link below for a larger picture.

Autumn Leaves-click to enlarge
Carotenoids are present in leaves the whole year round, but their orange-yellow colours are usually masked by green chlorophyll.  Carotenoids provide colourations of yellow, brown, orange, and the many hues in between.

The reds, the purples, and their blended combinations that decorate autumn foliage come from another group of pigments in the cells called anthocyanins. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer.   They develop in late summer in the sap of the cells of the leaf, and this development is the result of complex interactions of many influences — both inside and outside the plant. Their formation depends on the breakdown of sugars in the presence of bright light as the level of phosphate in the leaf is reduced.

The brown colour of leaves is not the result of a pigment, but rather cell walls, which may be evident when no colouring pigment is visible.

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Friday, 24 October 2014

On this day...

After the end of World War II on October 24, 1946 and a good while before the Sputnik satellite opened the space age, a group of soldiers and scientists in the New Mexico desert saw something new and wonderful—the first pictures of Earth as seen from space.

The White Sands rocket (official name V-2 No. 13) was the first man-made object to take a photograph of the Earth from outer space.   Launched from the White Sands Missile Range in White Sands, New Mexico, the rocket reached a maximum altitude of 107.5 miles (173 km), well above the commonly accepted boundary of space at 100 kilometres.

The famous photograph was taken from an altitude of 65 miles (104 km) with an attached 35 mm black-and-white camera.

Snapping a new frame every second and a half, the rocket-borne camera climbed straight up, then fell back to Earth minutes later, slamming into the ground at 500 feet per second. The camera itself was smashed, but the film, protected in a steel cassette, was unharmed.

It was one of many firsts for the V-2 research program of the late 1940s, during which the Army fired dozens of captured German missiles brought to White Sands in 300 railroad cars at the end of the war. While the missileers used the V-2s to refine their own rocket designs, scientists were invited to pack instruments inside the nosecone to study temperatures, pressures, magnetic fields and other physical characteristics of the unexplored upper atmosphere.

Earth from Space in colour

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Friday, 17 October 2014

pH Indicators

A pH indicator is a colour changing (or halochromic) chemical compound that is added in small amounts to a solution so that the pH (acidity or basicity) of the solution can be determined visually.
A pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+).  Normally, the indicator causes the colour of the solution to change depending on the pH.

pH (potential of hydrogen) is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is. More acidic solutions have lower pH. More alkaline solutions have higher pH. Substances which are not acidic or alkaline (neutral) usually have a pH of 7. Acids have a pH less than 7. Alkalis have a pH greater than 7.

pH indicator solutions are themselves weak acids or bases.  As one chemical is added it changes the arrangement of the electrons in the molecule causing it to absorb different wavelengths of light and therefore appear different in colour.

Different chemicals can be used for different pH ranges as shown in the diagram below.
pH indicators are frequently employed in titrations in analytical chemistry and biology to determine the extent of a chemical reaction. Because of the subjective choice (determination) of colour, pH indicators are susceptible to imprecise readings. For applications requiring precise measurement of pH, a pH meter is frequently used.
Many plants or plant parts contain chemicals from the naturally-coloured anthocyanin family of compounds. They are red in acidic solutions and blue in basic. Anthocyanins can be extracted with water or other solvents from a multitude of coloured plants or plant parts, including from leaves (red cabbage); flowers (geranium, poppy, or rose petals); berries (blueberries, blackcurrant); and stems (rhubarb). Extracting anthocyanins from household plants, especially red cabbage, to form a crude pH indicator is a popular introductory chemistry demonstration.
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Friday, 10 October 2014

On this day......Aspirin

On the 10th October 1897 German chemist Felix Hoffmann discovered an improved way of synthesizing acetylsalicylic acid or 'aspirin'.

Around c400 BC Hippocrates in Greece gives women willow leaf tea to relieve the pain of childbirth.  In 1763 Reverend Edward Stone of Chipping Norton near Oxford gives dried willow bark to 50 parishioners suffering rheumatic fever and describes his findings in a letter to the Royal Society of London.  In 1823 the active ingredient is extracted from willow and named salicin.  Salicylic acid is made from salicin by French scientists in 1853 butis found to irritate the gut.  In 1893 German scientists find that adding an acetyl group to salicylic acid reduces its irritant properties and in 1897 in Germany, Bayer's Felix Hoffmann develops and patents a process for synthesising acetyl salicylic acid or aspirin. First clinical trials begin.

Aspirin is often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication.

Aspirin is now accepted as an important weapon in the prevention of heart disease. A single dose of 300 mg is now recommended for patients in the acute stages of a heart attack followed by a daily dose of 75-100 mg. A similar low dose treatment regime is recommended for patients with angina, a history of heart problems or who have undergone coronary by pass surgery.

Aspirin is also used in other medical situations:-

  • Strokes - to reduce the risk

  • Pregnancy Complications - Pre-eclampsia and foetal growth retardation, both caused by blockages of the blood vessels of the placenta, are two of the commonest complications of pregnancy - aspirin helps to reduce this risk.
  • Colon cancer - In a long term study of 90,000 US nurses between 1976 and 1995, those who took 4-6 tablets of aspirin a week had a reduced incidence of colorectal cancer. The benefits were greatest in those who had taken the drugs the longest.
  • Diabetes - Blindness, coronary artery disease, stroke and kidney failure are all common complications of diabetes resulting from impaired blood circulation. The benefits of taking one aspirin a day are now so widely accepted that it is considered unethical to perform placebo controlled trials to prove the case.
  • Dementia (including Alzheimer's disease)- There is some evidence that aspirin may help prevent both the condition resulting from impaired blood flow and the most serious form of dementia, Alzheimer's disease.
The most common use is as a painkiller for headaches or fevers.

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Friday, 3 October 2014


Zinc is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element of group 12 of the periodic table. It’s the 24th most abundant element in the Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest mineable amounts are found in Australia, Asia, and the United States.

Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC.

Zinc is an essential mineral of "exceptional biologic and public health importance".  Zinc deficiency affects about two billion people in the developing world and is associated with many diseases.  In children it causes growth retardation, delayed sexual maturation, infection susceptibility, and diarrhoea, contributing to the death of about 800,000 children worldwide per year.

The metal is most commonly used as an anti-corrosion agent.  Galvanization, which is the coating of iron or steel to protect the metals against corrosion, is the most familiar form of using zinc in this way.  Zinc is more reactive than iron or steel and thus will attract almost all local oxidation until it completely corrodes away.  A protective surface layer of oxide and carbonate forms as the zinc corrodes.  This protection lasts even after the zinc layer is scratched but degrades through time as the zinc corrodes away.  The zinc is applied electrochemically or as molten zinc by hot-dip galvanizing or spraying. Galvanization is used on chain-link fencing, guard rails, suspension bridges, light posts, metal roofs, heat exchangers, and car bodies.

Zinc Oxide used in paint pigments

Zinc is useful for the human body and helps speed up the healing process after an injury.  It is also suspected of being beneficial to the body's immune system. Indeed, zinc deficiency may have effects on virtually all parts of the human immune system.

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Tuesday, 30 September 2014

The New OHAUS Adventurer Preview

Our blog is normally reserved for science news & facts and other interesting things!  However we thought we'd share this video featuring the new range of Ohaus Adventurer balances.  With dual USB ports, one at the front and one at the back connectivity is easy.  With colour touchscreen, fast stabilisation and accuracy these balances are worth a look.  Visit our website news page on the link below to download a brochure.

Visit http://www.prlabs.co.uk/news/article.php?Id=314

Friday, 26 September 2014

Flamin' hot colours!

Back in your school days there was probably an experiment where you placed a small amount of a compound into a flame and observed it's colour.  This is the flame test and depending on the colour observed it can tell you what elements are present.

Scientifically put, A flame test is an analytic procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each element's characteristic emission spectrum. The colour of flames in general also depends on temperature.

The test involves introducing a sample of the element or compound to a hot, non-luminous flame, and observing the colour of the flame that results. The idea of the test is that sample atoms evaporate and since they are hot, they emit light when being in flame.

The flame test is relatively quick and simple to perform, and can be carried out with the basic equipment found in most chemistry laboratories. However, the range of elements positively detectable under these conditions is small, as the test relies on the subjective experience of the experimenter rather than any objective measurements. The test has difficulty detecting small concentrations of some elements, while too strong a result may be produced for certain others, which tends to cause fainter colours to not appear.

Metal Ion Flame Tests-Click to enlarge
The table above from www.compoundchem.com shows the range of colours chemicals produce.  These tests work better for some metal ions than other; in particular, those ions shown on the bottom row of the infographic are generally quite faint and hard to distinguish. Sodium’s flame colour is also very strong, and can easily mask the colours of other metal ions.

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Friday, 19 September 2014

Sodium Hypochlorite

Sodium hypochlorite is a chemical compound with the formula NaClO. It is composed of a sodium cation (Na+) and a hypochlorite anion (ClO−); it may also be viewed as the sodium salt of hypochlorous acid. When dissolved in water it is commonly known as bleach or liquid bleach, and is frequently used as a disinfectant or a bleaching agent.

Click to enlarge

Potassium hypochlorite was first produced in 1789 by Claude Louis Berthollet in his laboratory on the quay Javel in Paris, France, by passing chlorine gas through a solution of potash lye. The resulting liquid, known as "Eau de Javel" ("Javel water"), was a weak solution of potassium hypochlorite. Antoine Labarraque replaced potash lye by the cheaper soda lye, thus obtaining sodium hypochlorite (Eau de Labarraque).

Various methods have been used since to produce this but the modern method, the Hooker process, is the only one producing this in any bulk capacity.

Sodium Hypochlorite has many uses as can be seen above:-

In bleach cleaning products and to remove stains.
In Swimming pools as a disinfectant.
In Antibacterial sprays
To neutralise nerve agents
To reduce skin damage - using very low concentrations.

Sodium Hypochlorite although used in household bleach is not the only component.  There is often Sodium Hydroxide and Calcium Hypochlorite amongst others.  it must be remembered not to mix household cleaning products as some may contain hydrochloric acid. If these are mixed with bleach, it can react with sodium hypochlorite, and form toxic chlorine gas

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Friday, 12 September 2014


Mercury is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum (from Greek "hydr-" water and "argyros" silver)

Mercury is remarkable because it is the only metal that is liquid at room temperature. It is a dense, lustrous grey metal. Mercury is extremely rare in the Earth's crust and in the wild, it typically is concentrated near volcanically active areas, either as the pure metal or in a number of minerals.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favour of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments.
The reason mercury was so popular is because it readily forms stable amalgams with a number of other metals, particularly silver and gold, making them workable at lower temperatures, and these amalgams have been the source of many instances of mercury poisoning.
Amalgam Filling
Biologists are quite interested in mercury because it is highly toxic to life, causing both acute and chronic poisoning. Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled. Mercury is concentrated in the body over the lifetime of the individual, and it also becomes more concentrated when one animal eats another, which is how it moves up the food chain. This is the reason why the flesh of tuna, a long-lived apex predator in the oceans, contain such high levels of mercury.
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Friday, 5 September 2014

Back to school

Where did the summertime break go?  Time for kids to go back to school.  And time for us too...chemistry basics.....Acids and bases

All acids:
  • have a low pH (1-6) – the lower the number the stronger the acid
  • react with bases to form neutral compounds
  • are corrosive when they are strong
  • are an irritant when they are weak.
Acids have a pH of less than 7. Bases have a pH of more than 7. When bases are dissolved in water, they are known as alkalis. Salts are made when an acid reacts with a base, carbonate or metal. The name of the salt formed depends on the metal in the base and the acid used. For example, salts made using hydrochloric acid are called chlorides.

Substances with a pH of less than 7 are acids. The more strongly acidic the solution, the lower its pH number. Acidic solutions turn blue litmus paper red. They turn universal indicator paper red if they are strongly acidic, and orange or yellow if they are weakly acidic.

Substances that can react with acids and neutralise them to make a salt and water are called bases. They are usually metal oxides or metal hydroxides. For example, copper oxide and sodium hydroxide are bases.

Bases that dissolve in water are called alkalis. Copper oxide is not an alkali because it does not dissolve in water. Sodium hydroxide is an alkali because it does dissolve in water.

Alkaline solutions have a pH of more than 7. The stronger the alkali, the higher the pH number. Alkalis turn red litmus paper blue. They turn universal indicator paper dark blue or purple if they are strongly alkaline, and blue-green if they are weakly alkaline.

Neutral solutions
Neutral solutions have a pH of 7. They do not change the colour of litmus paper, but they turn universal indicator paper green. Water is neutral.

For pH meters or pH test papers or buffer solutions give us a call.

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Friday, 29 August 2014

Red hot chilli peppers!!!

The chilli pepper or chilli is the fruit of plants from the genus Capsicum.  The substances that give chili peppers their intensity when ingested or applied topically are capsaicin (8-methyl-N-vanillyl-6-nonenamide) and several related chemicals, collectively called capsaicinoids.
Cayenne pepper

Chili peppers originated in the Americas but spread around the world and India is now the world's largest producer, consumer and exporter of chili peppers.

When consumed, capsaicinoids bind with pain receptors in the mouth and throat that are responsible for sensing heat. Once activated by the capsaicinoids, these receptors send a message to the brain that the person has consumed something hot. The brain responds to the burning sensation by raising the heart rate, increasing perspiration and release of endorphins.

The "heat" of chili peppers was historically measured in Scoville heat units (SHU), which is a measure of the dilution of an amount of chili extract added to sugar syrup before its heat becomes undetectable to a panel of tasters; the more it has to be diluted to be undetectable, the more powerful the variety and therefore the higher the rating.  The modern commonplace method for quantitative analysis of SHU rating uses high-performance liquid chromatography to directly measure the capsaicinoid content of a chili pepper variety. Pure capsaicin is a hydrophobic, colorless, odorless, and crystalline-to-waxy solid at room temperature, and measures 16,000,000 SHU.

Chemistry of a Chilli-click to enlarge

Capsaicin extracted from chillis is also used in pepper spray as an irritant, a form of less-lethal weapon.

Red chilies contain large amounts of vitamin C and small amounts of carotene (provitamin A). Yellow and especially green chilies (which are essentially unripe fruit) contain a considerably lower amount of both substances. In addition, peppers are a good source of most B vitamins, and vitamin B6 in particular. They are very high in potassium, magnesium, and iron. Their very high vitamin C content can also substantially increase the uptake of non-heme iron from other ingredients in a meal, such as beans and grains.

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Friday, 22 August 2014


It's still summer - or at least it was sunny when I wrote this.  Knowing the British weather it could be raining now.  However rain doesn't always stop the effects of hayfever.


Allergic rhinitis is an allergic inflammation of the nasal airways. It occurs when an allergen, such as pollen, dust or animal dander (particles of shed skin and hair) is inhaled by an individual with a sensitized immune system. In such individuals, the allergen in affected individuals is mistakenly identified as a threat and triggers the production of the antibody immunoglobulin E (IgE), which binds to mast cells and basophils containing histamine. When caused by pollens of any plants, it is called pollinosis, and, if specifically caused by grass pollens, it is known as hay fever. While symptoms resembling a cold or flu can be produced by an allergic reaction to pollen from plants and grasses it does not cause a fever.

IgE bound to mast cells are stimulated by allergens, causing the release of inflammatory mediators such as histamine (and other chemicals). This usually causes sneezing, itchy and watery eyes, swelling and inflammation of the nasal passages, and an increase in mucus production.
To reduce the symptoms of hayfever science has developed a number of medications to alleviate or prevent the symptoms.  A fantastic website (Compound Interest) goes into this in much more detail including the amazing infographic below.

Click to enlarge

Antihistamine drugs include those such as cetirizine and loratadine. They work by binding to the H1 receptors that histamine usually binds to, preventing it from inducing an inflammatory response to the allergens.  As you can see from the infographic above some drugs must be taken before symptoms appear for them to be effective.  Click here for a full screen image.

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Friday, 15 August 2014

What is Brownian Motion?

The term 'Brownian motion' (or 'Brownian movement') refers to the apparently random, haphazard movement of microscopic particles which are suspended in a fluid - (a liquid or a gas) resulting from their collision with the quick atoms or molecules in the gas or liquid.

This is a simulation of the Brownian motion of a big particle (dust particle) that collides with a large set of smaller particles (molecules of a gas) which move with different velocities in different random directions.
Although a number of earlier workers had observed this phenomenon, it was first described, and therefore named after, the British botanist, Robert Brown, who was studying pollen grains in 1827. Brown was an accomplished microscopist. It was he who, for example, first identified the naked ovule in the gymnospermae; this is a difficult observation to make even with a modern instrument.

Brown was attempting to further his work on the mechanisms of fertilisation in flowering plants and was looking at pollen.  He believed that he would be able to examine the pollen grains more effectively through his microscope if they were suspended in water, a technique known as 'water-immersion'. To his annoyance, he observed that the pollen grains danced continuously and erratically around in the water, thus interfering with his observations. From these observations he satisfied himself that the movement:

'arose neither from currents in the fluid, nor from its gradual evaporation, but belonged to the particle itself'.

Decades later, Albert Einstein published a paper in 1905 that explained in precise detail how the motion that Brown had observed was a result of the pollen being moved by individual water molecules.

Despite all of this knowledge, scientists continue to be fascinated by the origin and nature of Brownian motion, which is still imperfectly understood. Articles concerning the mathematics of Brownian motion continue to be published in contemporary physics journals.

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Friday, 8 August 2014

1000mph - along the ground - Bloodhound SSC.

BLOODHOUND SSC is a SuperSonic Car.  It's supersonic because it is designed to go faster than the speed of sound and it's a car because it has four wheels and is under full control of its driver.

BLOODHOUND SSC is a jet and rocket powered car designed to go at 1,000 mph (just over 1,600 kph). It has a slender body of approximately 14m length with two front wheels within the body and two rear wheels mounted externally within wheel fairings. It weighs over 7 tonnes and the engines produce more than 135,000 horsepower - more than 6 times the power of all the Formula 1 cars on a starting grid put together!

The Car is a mix of car and aircraft technology, with the front half being a carbon fibre monocoque like a racing car and the back half being a metallic framework and panels like an aircraft.

Runway testing of up to 200 miles per hour (320 km/h) is scheduled to take place early 2016. Bloodhound SSC will then be tested on the Hakskeen Pan in the Mier area of the Northern Cape, South Africa where a track 12 miles (19 km) long, 2 miles (3.2 km) wide has been cleared.

The car is an amazing feat of engineering.  A prototype Eurojet EJ200 jet engine developed for the Eurofighter and bound for a museum, was donated to the project. This will take the car to 300 mph (480 km/h), after which a bespoke hybrid rocket designed by Nammo will boost the car up to 1,000 miles per hour (1,609 km/h). A third engine, a 750 hp (560 kW) 2.4 Litre Cosworth CA2010 Formula 1 V8 petrol engine, is used as an auxiliary power unit and to drive the oxidiser pump for the rocket. The jet engine will provide nine tonnes of thrust and the rocket will add another 12. The supersonic car will have roughly the same power as 180 F1 cars.

The Bloodhound SSC project has a comprehensive website as below:-

They are on Twitter and regularly post updates.  An example is the fascinating infographic below - 10 astounding facts about Bloodhound SSC.

Be sure to keep up to date and follow the Bloodhound SSC project.