P&R Labpak - Everything for your laboratory

P&R Labpak - Everything for your laboratory
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Friday, 29 March 2013

Easter Eggs!!!

Easter eggs are special eggs that are often given to celebrate Easter or springtime.

Eggs, in general, were a traditional symbol of fertility, and rebirth, pre-dating Christian traditions. The practice of decorating eggshell is ancient. Ostrich eggs with engraved decoration that are 60,000 years old have been found in Africa. Decorated ostrich eggs, and representations of ostrich eggs in gold and silver, were commonly placed in graves of the ancient Sumerians and Egyptians as early as 5,000 years ago.

Although the tradition is to use dyed or painted chicken eggs, a modern custom is to substitute chocolate eggs, or plastic eggs filled with confectionery.

 


Various games are played at Easter time with eggs.

Egg rolling is also a traditional Easter egg game played with eggs at Easter. In the United Kingdom, Germany, and other countries children traditionally rolled eggs down hillsides at Easter. This tradition was taken to the New World by European settlers and continues to this day each Easter on the White House lawn.

Different nations have different versions of the game

An Easter egg is also an intentional hidden message, inside joke, or feature in a work such as a computer program, movie, book, or crossword. Easter eggs are also found on movie DVDs.
Have a pleasant Easter break!

Friday, 22 March 2013

The Mobius Strip!

The Mobius Strip

The Mobius strip is a topological device with many amazing properties. You can make one from a simple strip of paper.

To make your very own Mobius strip simply take a paper strip, giving it a half twist and then joining the ends together to form a loop.
No matter how you twist or bend a Mobius strip (short of tearing it in two and glueing it back together again) you'll never be able to get rid of that twist and turn it into just a normal loop.
 
The Mystery of the Mobius
But what's so special about this strip? Try colouring one side of your strip green and the other side yellow. You'll find that you just end up colouring the whole thing a dull blue. Why is that? Because the most amazing thing about the Mobius strip is that it only has one side. A line drawn starting from the seam down the middle will meet back at the seam but at the "other side". If continued the line will meet the starting point and will be double the length of the original strip. This single continuous curve demonstrates that the Möbius strip has only one boundary.
This is where the symbol for infinity comes from. The sideways figure 8 you see, meaning infinity, is actually supposed to represent a Mobius strip, since the Mobius strip goes on forever.
More Fun With Your Mobius

Try to cut it in half to make two of them. Draw completely around the centreline of your strip. Remember that you won't need to lift the pen to do both sides. Then get a sharp knife or a pair of scissors and cut along the line. When you get back to the start of your cut after cutting all the way around the strip.
You'll find that you can't cut your Mobius strip in two at all. You've still just got one long loop with a couple of extra twists thrown in for good measure.
Try cutting it in two again. Do it the same way - all the way around the strip, and this time you really do get two strips. But the Mobius strip still has another trick up its topological sleeve. The two strips you now have are linked together!

What use is it?

There have been several technical applications for the Mobius strip. Giant Mobius strips have been used as conveyor belts that last longer because the entire surface area of the belt gets the same amount of wear, and as continuous-loop recording tapes (to double the playing time). Mobius strips are common in the manufacture of fabric computer printer and typewriter ribbons, as they allow the ribbon to be twice as wide as the print head while using both halves evenly.
A Mobius Scarf

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Friday, 15 March 2013

Nitric Acid

Nitric acid (HNO3), also known as aqua fortis and spirit of niter, is a highly corrosive strong mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. Most commercially available nitric acid has a concentration of 68%. When the solution contains more than 86% HNO3, it is referred to as fuming nitric acid. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as white fuming nitric acid or red fuming nitric acid, at concentrations above 95%. Nitric acid is also commonly used as a strong oxidizing agent.

Contamination with nitrogen dioxide
 
Nitric acid is subject to thermal or light decomposition: 4 HNO3 → 2 H2O + 4 NO2 + O2. This reaction may give rise to some non-negligible variations in the vapor pressure above the liquid because the nitrogen oxides produced dissolve partly or completely in the acid.

Uses

The main use of nitric acid is for the production of fertilisers. Nitric acid is neutralised with ammonia to give ammonium nitrate. This application consumes 75-80% of the 26M tons produced annually (1987). The other main applications are for the production of explosives, nylon precursors, and specialty organic compounds.

Other Uses

As an analytical reagent - In elemental analysis by ICP-MS, ICP-AES, GFAA, and Flame AA, dilute nitric acid (0.5 to 5.0%) is used as a matrix compound for determining metal traces in solutions.  Ultrapure trace metal grade acid is required for such determination, because small amounts of metal ions could affect the result of the analysis.

It is also typically used in the digestion process of turbid water samples, sludge samples, solid samples as well as other types of unique samples which require elemental analysis.

In electrochemistry, nitric acid is used as a chemical doping agent for organic semiconductors, and in purification processes for raw carbon nanotubes.

Woodworking - In a low concentration (approximately 10%), nitric acid is often used to artificially age pine and maple. The color produced is a grey-gold very much like very old wax or oil finished wood

Etchant and cleaning agent - The corrosive effects of nitric acid are exploited for a number of specialty applications, such as etching of metals to reveal the microstructure.

Concentrated nitric acid is required for many chemical processes. It is produced by feeding the aqueous nitric acid resulting from the oxidation of ammonia (composition about 65% HNO3 by mass), into a concentration unit along with 60 - 67% by mass of concentrated sulphuric acid, H2SO4.

P&R Labpak can supply a wide range of Nitric Acids of different grades and quantities.

For more information on Nitric Acid:-

http://en.wikipedia.org/wiki/Nitric_acid
http://www.greener-industry.org.uk/
http://www.prlabs.co.uk/search.php


Friday, 8 March 2013

The Periodic Table


The Periodic Table

A periodic table is a tabular display of the chemical elements, organized on the basis of their atomic numbers, electron configurations, and recurring chemical properties. Elements are presented in order of increasing atomic number (number of protons). The standard form of table comprises an 18 × 7 grid or main body of elements, positioned above a smaller double row of elements. The table can also be deconstructed into four rectangular blocks: the s-block to the left, the p-block to the right, the d-block in the middle, and the f-block below that. The rows of the table are called periods; the columns of the s-, d-, and p-blocks are called groups, with some of these having names such as the halogens or the noble gases. Since, by definition, a periodic table incorporates recurring trends, any such table can be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table—whether in the standard form or some other variant—provides a useful framework for analyzing chemical behavior, and such tables are widely used in chemistry and other sciences.

 
Although precursors exist, Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table. He developed his table to illustrate periodic trends in the properties of the then-known elements. Mendeleev also predicted some properties of then-unknown elements that would be expected to fill gaps in this table. Most of his predictions were proved correct when the elements in question were subsequently discovered. Mendeleev's periodic table has since been expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour.
 

Download a copy here.

http://en.wikipedia.org/wiki/Periodic_table
http://iupac.org/

Friday, 1 March 2013

What is a Barometer?


A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries.

 
Evangelista Torricelli is universally credited with inventing the barometer in 1643.

Mercury barometers
A mercury barometer has a glass tube with a height of at least 84 cm, closed at one end, with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature at the instrument will reduce the density of the mercury, the scale for reading the height of the mercury is adjusted to compensate for this effect.

In 1646, Blaise Pascal along with Pierre Petit, had repeated and perfected Torricelli's experiment and went even further to test the mechanical theory. If, as suspected by mechanical philosophers like Torricelli and Pascal, air had lateral weight, the weight of the air would be less at higher altitudes. Therefore, Pascal wrote to his brother-in-law, Florin Perier, who lived near a mountain called the Puy de Dome, asking him to perform a crucial experiment. Perier was to take a barometer up the Puy de Dome and make measurements along the way of the height of the column of mercury. He was then to compare it to measurements taken at the foot of the mountain to see if those measurements taken higher up were in fact smaller. In September 1648, Perier carefully and meticulously carried out the experiment, and found that Pascal's predictions had been correct. The mercury barometer stood lower the higher one went

Aneroid Barometers
An aneroid barometer, invented in 1843 by French scientist Lucien Vidie uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper. The evacuated capsule (or usually more capsules) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. Many models include a manually set needle which is used to mark the current measurement so a change can be seen. In addition, the mechanism is made deliberately "stiff" so that tapping the barometer reveals whether the pressure is rising or falling as the pointer moves.
 
Changes in atmospheric pressure are one of the most commonly used ways to forecast changes in the weather because weather patterns are carried around in regions of high and low pressure. Weather maps use lines of equal pressure called isobars to indicate areas of equal pressure.

A slowly rising atmospheric pressure, over a week or two, typically indicates settled weather that will last a long time. A sudden drop in atmospheric pressure over a few hours often forecasts an approaching storm, which will not last long, with heavy rain and strong winds.

By carefully watching the pressure on a barometer, you can forecast local weather using these simple guidelines:

·         Decreasing barometric pressure indicates storms, rain and windy weather.
·         Rising barometric pressure indicates good, dry, and colder weather.
·         Slow, regular and moderate falls in pressure suggest a low pressure area is passing in a nearby region. Marked changes in the weather where you are located are unlikely.
·         Small rapid decreases in pressure indicate a nearby change in weather. They are usually followed by brief spells of wind and showers.
·         A quick drop in pressure over a short time indicates a storm is likely in 5 to 6 hours.
·         Large, slow and sustained decreasing pressure forecasts a long period of poor weather. The weather will be more pronounced if the pressure started rising before it began to drop.
·         A rapid rise in pressure, during fair weather and average, or above average pressure, indicates a low pressure cell is approaching. The pressure will soon decrease forecasting poorer weather.
·         Quickly rising pressure, when the pressure is low, indicates a short period of fair weather is likely.
·         A large, slow and sustained rise in pressure forecasts a long period of good weather is on its way.

For more information:-