Monthly Archives: January 2014

What is absolute zero?

In theory, absolute zero is the temperature where the particles of matter stop moving. Absolute zero is impossible to achieve, because all particles move, even if it is just a small vibration. Some people have created temperatures very close to absolute zero, but the record temperature was 100 pK (Picokelvin) above absolute zero.  Even getting close to absolute zero is difficult because anything that touches an object being cooled near absolute zero would give heat to the objects. Scientists use lasers to slow atoms when cooling objects to very low temperatures.

The Kelvin and Rankine temperature scales are defined so that absolute zero is 0 kelvins (K) or 0 degrees Rankine (°R). The Celsius and Fahrenheit scales are defined so that absolute zero is −273.15 °C or −459.67 °F.

At this stage the pressure of the particles is zero. If we plot a graph to it, we can see that the temperature of the particles is zero. The temperature cannot go down any further. Also, the particles cannot move in “reverse” either because as the movement of particles is vibration, vibrating in reverse would be nothing but simply vibrating again. The closer the temperature of an object gets to absolute zero, the less resistive the material is to electricity therefore it will conduct electricity almost perfectly, with no measurable resistance.

The Third Law of Thermodynamics says that nothing can ever have a temperature of absolute zero.

The Second Law of Thermodynamics says that all engines that are powered by heat (like car engines and steam train engines) must release waste heat and can not be 100% efficient. This is because the efficiency (percent of energy the engine uses up that is actually used to do the engine’s job) is 100%×(1-Toutside/Tinside), which only is 100% if the outside temperature is absolute zero which it can not be. So, an engine can not be 100% efficient, but you can make its efficiency closer to 100% by making the inside temperature hotter and/or the outside temperature colder.

In September 2013, MIT scientists cooled a sodium gas to the lowest temperature ever recorded — only half-a-billionth of a degree above absolute zero.

Absolute zero is defined to be −273.15°C, or 0 K.

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A word in your shell like…..

Ever put a sea shell to your ear and listened to the sea?  You’ve probably done it when you were young but have you ever wondered what it was you were listening to?

There are a number of ideas about what actually makes the ‘wave’ sound when you put a shell to your ear. One suggestion is that you’re hearing the echo of your heart beating and the blood rushing around your body, in particular the blood vessels in your ear. But that’s simply not true, because if you ran about a lot before putting the shell to your ear there would be a definite difference in the intensity of the ‘waves’ you hear. Why? Well, exercise of any sort increases you heart rate hence the waves would be louder, or more frequent, in time with the faster beating of your heart.

Another explanation is that the wave sound is created by air flowing through the shell, and this may have a little to do with it as the sound becomes louder when you lift the shell slightly away from your ear. However, if you put your ear to a shell in a soundproof room (where there is no ambient noise, but air is still cycling around the shell), the wave sound is noticeably missing. So, it must have something to do with outside noise.

When you hold up a shell to your ear, you block out direct noise to your ear. However, the shell captures any atmospheric noise, which then resonates inside the shell. This resonating chamber needs some noise to work with, but otherwise works regardless of whether your surroundings are noisy or not. However, it stands to reason that the louder the environment around you, the louder the sound inside the shell – as more sound waves are ‘bouncing’, for want of a better term, around the chamber. These frequencies are garbled by the walls of the chamber and become like radio static to us, as our ear is not finely tuned enough to distinguish every nuance. Thus you get that shhhhhh sound, like waves breaking on the sea shore.

The rushing sound that one hears is in fact the noise of the surrounding environment, resonating within the cavity of the shell. The same effect can be produced with any resonant cavity, such as an empty cup or even by simply cupping one’s hand over one’s ear. The similarity of the noise produced by the resonator to that of the oceans is due to the resemblance between ocean movements and airflow.

Noise from outside the shell also can change the intensity of the sound you hear inside the shell. You can look at the shell as a resonating chamber. When sound from outside enters the shell, it bounces around, thus creating an audible noise. So, the louder the environment you are in, the louder the ocean-like sound will be.

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Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth’s crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-grey metal.

Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewellery and paints, and to tint glass blue, but the colour was later thought by alchemists to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment producing minerals; they were named because they were poor in known metals, and gave poisonous arsenic-containing fumes upon smelting. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.

Cobalt is primarily used as the metal, in the preparation of magnetic, wear-resistant and high-strength alloys. Its compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes.

Cobalt blue tinted glass

Free cobalt (the native metal) is not found in on Earth, except as recently delivered in meteoric iron (see below). Though the element is of medium abundance, natural compounds of cobalt are numerous. Small amounts of cobalt compounds are found in most rocks, soil, plants, and animals.

Cobalt forms many useful alloys. It is alloyed with iron, nickel, and other metals to form Alnico, an alloy with exceptional magnetic strength. Cobalt, chromium, and tungsten may be alloyed to form Stellite, which is used for high-temperature, high-speed cutting tools and dies. Cobalt is used in magnet steels and stainless steels. It is used in electroplating because of its hardness and resistance to oxidation. Cobalt salts are used to impart permanent brilliant blue colours to glass, pottery, enamels, tiles, and porcelain. Cobalt is used to make Sevre’s and Thenard’s blue. A cobalt chloride solution is used to make a sympathetic ink. Cobalt is essential for nutrition in many animals. Cobalt-60 is an important gamma source, tracer, and radiotherapeutic agent.

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18 years ago today – the Kobe Earthquake – Japan

Eighteen years ago to the day the Kobe earthquake shook Japan.  The Great Hanshin earthquake occurred on Tuesday, January 17, 1995, at 05:46 JST in the southern part of Japan. It measured 6.8 on the moment magnitude scale (USGS), and Mj7.3 (adjusted from 7.2) on JMA magnitude scale.  The tremors lasted for approximately 20 seconds. The focus of the earthquake was located 16 km beneath its epicentre, on the northern end of Awaji Island, 20 km away from the city of Kobe.

An earthquake is a quick release of energy in the Earth’s crust, creating seismic waves. The Earth’s crust is made up of tectonic plates. The tectonic plate edges move against each other all the time, but sometimes they get stuck. When this happens energy builds up to a point of rupture and the seismic energy is released.

The depth of an earthquake is very important.  If it is shallow it will cause much more structural damage to buildings than a deep one. On the Earth’s surface an earthquake will manifest itself by shaking buildings and the ground moving. If an earthquake occurs at sea it can move and displace the seabed. The water on the seabed of an ocean or large lake is normally very still, with waves only occurring near the surface, but if the seabed moves it can cause a deep and harmful that can result in a tsunami as happened in Japan in 2011.

In the Kobe earthquake, approximately 6,434 people lost their lives (final estimate as of December 22, 2005); about 4,600 of them were from Kobe.

A section of the Nojima Fault

The Great Hanshin earthquake belonged to a third type, called an “inland shallow earthquake”. Earthquakes of this type occur along active faults. Even at lower magnitudes, they can be very destructive because they often occur near populated areas and because their hypocenters are located less than 20 km below the surface. The Great Hanshin earthquake began north of the island of Awaji, which lies just south of Kobe. It spread toward the southwest along the Nojima Fault on Awaji and toward the northeast along the Suma and Suwayama faults, which run through the center of Kobe. Observations of deformations in these faults suggest that the area was subjected to east-west compression, which is consistent with previously known crustal movements.

The earthquake proved to be a major wake-up call for Japanese disaster prevention authorities. Japan installed rubber blocks under bridges to absorb the shock and rebuilt buildings further apart to prevent them from falling like dominoes. The national government changed its disaster response policies in the wake of the earthquake, and its response to the 2004 Chūetsu earthquake was significantly faster and more effective.  The earthquake and tsunami of 2011 though was much larger than anything that had been seen before causing almost 16,000 deaths.  There was little that could be done to stop such a force of nature.

A large amount of data was collected after the tsunami of 2011 that provides “the possibility to model in great detail what happened during the rupture of an earthquake.” The effect of this data is expected to be felt across other disciplines as well, and this disaster will “provide unprecedented information about how buildings hold up under long periods of shaking – and thus how to build them better.

Earthquakes can strike at any time and are unpredictable in their nature.  Fortunately these types of earthquake are not that common.  Early warning systems are in place for many countries around earthquake hot spots so as to try and give people time to get to safety.

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Acetic Acid – Vinegar to you and me…..

Acetic acid is an organic compound with the chemical formula CH3COOH.  It’s a colourless liquid that when undiluted is also called glacial acetic acid.

Acetic acid is the main component of vinegar (apart from water; vinegar is roughly 8% acetic acid by volume), and has a distinctive sour taste and pungent smell. Besides its production as household vinegar, it is mainly produced as a precursor to the manufacture of polyvinyl acetate and cellulose acetate – used in wood glue & fabrics and for photographic films respectively. Although it is classified as a weak acid, concentrated acetic acid is corrosive and attacks the skin.

Acetic Acid as Vinegar is known as the food additive E260.

Glacial acetic acid is the name for water-free (anhydrous) acetic acid. Similar to the German name Eisessig (ice-vinegar).  The theoretical freezing point of glacial acetic acid is 16.7 degrees Celcius. It got it’s name because it’s freezing point is only slightly below room temperature.

Glacial Acetic Acid

Vinegar was known early in civilization as the natural result of air exposure to beer and wine, because acetic acid-producing bacteria are present globally.

Vinegar is typically 4-18% acetic acid by mass. Vinegar is used directly as a condiment, and in the pickling of vegetables and other foods. Table vinegar tends to be more diluted (4% to 8% acetic acid), while commercial food pickling employs solutions that are more concentrated. The amount of acetic acid used as vinegar on a worldwide scale is not large, but is by far the oldest and best-known application.

Concentrated acetic acid is corrosive to skin and must, therefore, be handled with appropriate care, since it can cause skin burns, permanent eye damage, and irritation to the mucous membranes. These burns or blisters may not appear until hours after exposure. Latex gloves offer no protection, so specially resistant gloves, such as those made of nitrile rubber, are worn when handling the compound.

White vinegar is also known as distilled vinegar and is used for medicinal, laboratory, and cleaning purposes, having some anti-bacterial properties, as well as in cooking, baking, meat preservation, and pickling.

As you can see Acetic Acid is available in many strengths and so is suitable for food applications, cleaning applications (using white vinegar for example) to industrial applications and use in laboratories.

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