Pipettes and BurettesI thought this would be a good question to share:
What is the difference between a pipette and burette? My assessment book said a pipette was used to measure specific volumes of liquids to an accuracy of 0.1cm3 while a burette was to measure volumes of liquids to an accuracy of 0.1cm3...
What does it mean by specific? Is there a difference? I would also like to know: what do you use to measure what liquid and when do you use it? Anyone care to enlighten me? :)
This is posted on the discussion forum...I would like to know what the difference is.
Oh and in case you didn't know what they were, here's some research I did...(:
BuretteA burette is a vertical cylindrical piece of
laboratory glassware with a volumetric graduation on its full length and a precision tap, or
stopcock, on the bottom. It is used to dispense known amounts of a
liquid reagent in
experiments for which such
precision is necessary, such as a
titration experiment. Burettes are extremely accurate.
Pipette A pipette is a laboratory instrument used to transport a measured volume of
liquid.Pipettes are commonly used in
chemistry and
molecular biology research as well as
medical tests. Pipettes come in several designs for various purposes with differing levels of
accuracy and precision, from single piece glass pipettes to more complex adjustable or electronic pipettes. A pipette works by creating a
vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid.
Taken from: wikipedia.org
Denses Element
What is the densest element?
Some websites say that osmium is the densest material. Others say irridium is. Which is denser? First, let's find out what they even are.
Osmium
This metal is lustrous, bluish white, extremely hard, and brittle even at high temperatures. It has the highest melting point and the lowest vapour pressure of the platinum group. The metal is very difficult to fabricate, but the powdered or spongy metal slowly gives off osmium tetroxide, which as a powerful oxidising agent and has a strong smell. The tetroxide is highly toxic, and boils at 130 degrees celcius.
Irridium
Iridium is white but with a slight yellowish cast. Because iridium is very hard and brittle, it is hard to machine, form, or work. It is the most corrosion-resistant metal known, and was used in making the standard meter bar of Paris, which is a 90 percent platinum and 10 percent iridium alloy.
So...which is heavier??
The measured densities of iridium and osmium seem to indicate that osmium is slightly more dense than iridium, so osmium has generally been credited with being the heavier element. Calculations of the density from the space lattice which may be more reliable for these elements than actual measurements, however, give a density of 22.65 for iridium compared to 22.661 for osmium. Despite this information, no decision has been made as to which is heavier.
ArchimedesArchimedes was a Greek mathematician, physicist, engineer, inventor, and astronomer.
Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and the explanation of the principle of the lever. He is credited with designing innovative machines, including siege engines and the screw pump that bears his name. Modern experiments have tested claims that Archimedes designed machines capable of lifting attacking ships out of the water and setting ships on fire using an array of mirrors.
Archimedes is generally considered to be the greatest mathematician of antiquity and one of the greatest of all time. He used the method of exhaustion to calculate the area under the arc of a parabola with the summation of an infinite series, and gave a remarkably accurate approximation of pi. He also defined the spiral bearing his name, formulas for the volumes of surfaces of revolution and an ingenious system for expressing very large numbers.
Archimedes died during the Siege of Syracuse when he was killed by a Roman soldier despite orders that he should not be harmed. Cicero describes visiting the tomb of Archimedes, which was surmounted by a sphere inscribed within a cylinder. Archimedes had proven that the sphere has two thirds of the volume and surface area of the cylinder.
Taken from: Wikipedia.org
Some of his Discoveries and InventionsThe Golden CrownThe most widely known anecdote about Archimedes tells of how he invented a method for determining the volume of an object with an irregular shape.
A new crown in the shape of a laurel wreath had been made for King Hiero II, and Archimedes was asked to determine whether it was of solid gold, or whether silver
had been added by a dishonest goldsmith. Archimedes had to solve the problem without damaging the crown, so he could not melt it down into a regularly shaped body in order to calculate its density. While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realized that this effect could be used to determine the volume of the crown. For practical purposes water is incompressible, so the submerged crown would displace an amount of water equal to its own volume. By dividing the weight of the crown by the volume of water displaced, the density of the crown could be obtained. This density would be lower than that of gold if cheaper and less dense metals had been added. Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!"
The Claw of ArchimedesThe Claw of Archimedes is a weapon that he is said to have designed in order to defend the city of Syracuse. Also known as "the ship shaker," the claw
consisted of a crane-like arm from which a large metal grappling hook was suspended. When the claw was dropped onto an attacking ship the arm would swing upwards, lifting the ship out of the water and possibly sinking it. There have been modern experiments to test the feasibility of the claw, and in 2005 a television documentary entitled Superweapons of the Ancient World built a version of the claw and concluded that it was a workable device.
Pipettes and Burettes
liquid.Pipettes are commonly used in chemistry and molecular biology research as well as medical tests. Pipettes come in several designs for various purposes with differing levels of accuracy and precision, from single piece glass pipettes to more complex adjustable or electronic pipettes. A pipette works by creating a vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid.
Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and the explanation of the principle of the lever. He is credited with designing innovative machines, including siege engines and the screw pump that bears his name. Modern experiments have tested claims that Archimedes designed machines capable of lifting attacking ships out of the water and setting ships on fire using an array of mirrors.
had been added by a dishonest goldsmith. Archimedes had to solve the problem without damaging the crown, so he could not melt it down into a regularly shaped body in order to calculate its density. While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realized that this effect could be used to determine the volume of the crown. For practical purposes water is incompressible, so the submerged crown would displace an amount of water equal to its own volume. By dividing the weight of the crown by the volume of water displaced, the density of the crown could be obtained. This density would be lower than that of gold if cheaper and less dense metals had been added. Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" 
consisted of a crane-like arm from which a large metal grappling hook was suspended. When the claw was dropped onto an attacking ship the arm would swing upwards, lifting the ship out of the water and possibly sinking it. There have been modern experiments to test the feasibility of the claw, and in 2005 a television documentary entitled Superweapons of the Ancient World built a version of the claw and concluded that it was a workable device.
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