Avogadro's Number Lab

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  • Topic: Atom, Mole, Avogadro constant
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  • Published : October 26, 2011
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Chemistry Lab

Avogadro’s Number Labs

Avogadro’s number was obtained using information based on the thickness of the stearic acid monolayer. Once mass was found, volume of the acid was obtained in both trials, .000076 cm^3 and .000068cm^3 respectively. Then area was calculated 214cm^2 and 230cm^2 respectively. Thickness could be calculated with that data and it came out to .00000036cm and .00000030cm respectively. By dividing the thickness by 18, the height of one carbon atom was calculated to be .000000020cm and .000000017cm. Volume of one carbon atom was calculated by cubing that number to get 8.0x10^24 and 4.9x10^24. Then 3.42mol was used (volume of one mol of carbon) to calculate the number of atoms per mole (by dividing Vmol/Vatom) and the final results were 4.3x10^23 and 7.0x10^23. This same process was used in part II and 5.8x10^23 was calculated as the answer.

Methods Section:
In part I, Avogadro’s number was calculated by finding using the thickness of the Stearic Acid monolayer. The height of one carbon atom was used to find the volume of a carbon atom, then the volume of one mol of carbon was calculated. With both of these numbers, Vmol was divided by Vatom to obtain Avogadro’s number. In part II, the thickness of a piece of aluminum foil was used to find Avogadro’s number. Thickness was calculated by using the equation Volume/Area. Height was calculated using information given, which was the atomic radius of an aluminum atom to be 143pm. Multiply it by two to get diameter. The diameter is then taken and multiplied by 1.35, which is the percent efficiency. With that number you calculate the volume of the mol of aluminum and the volume of the aluminum atom. Divide Vmol/Vatom and you get Avogadro’s number.
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