Avogadro's Number Lab Report

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How was Avogadro’s number determined? Jessica Kim 12D Starting from 200 years ago, scientists tried to figure out the basic ideas of chemistry. One of them they put lots of effort in was to find out the mass of the smallest particle, mole. Measuring the mass was a primary difficulty at that time since one mole of a substance was unable to weigh without using developed technology. Even though, it was clear that everything was made out of a small unit, there was no evidence that could determine what it was and how to measure it. So, as most scientific ideas had to be created with indirect evidence, it was difficult for theories to develop further. Therefore, the discovery of the mass of one mole, Avogadro’s number, was very important in chemistry.…show more content…
Jean Baptiste Perrin first used the term ‘Avogadro’s number’, in 1909. He made an estimate of the Avogadro’s number during his experiment of Brownian motion- microscopic particles suspended in a liquid or gas moving randomly. Figure 1 shows the movement of molecules Perrin investigated by looking of pollens floating on water through a microscope. The value he gained was 7.05x 1023 mol-1 , which is not a very far value from what we use these days. Through his experiment, confusion was about atoms and molecules have finished and the existence of molecules was proved. Figure 1 Jean Baptiste Perrin (left)& Movement of the molecules following Brownian motion (right) The measurement of a single quantity on both atomic and macroscopic scales using the same unit of measurement is required to find out accurate values of Avogadro’s number. The discovery to measure the charge of an electron made this possible for the first time by Robert Millikan. Avogadro’s number can be measured if the charge on a mole of electrons is divided by the charge on a single electron. Another method is to use density of an ultrapure sample of a material on the macroscopic scale. X-ray diffraction techniques are used to find the density on the atomic scale and the number of atoms in the crystal is determined. Also, the distance between the equivalent points that define the unit cell can be used to measure the Avogadro’s
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