Given a pure copper penny of radius 0.90 cm and thickness 0.145 cm, calculate th

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The plan to solve this is as follows: solve for volume->use density to solve for mass->use molar mass to convert to moles-> use avogadros number to solve for number of atoms. 1) the equation of the area of a cirgcle is pi x radius^2 . multiply that by the thickness to get volume. pi x .9^2 = 2.55 cm^2. multiplyed by .145 gives you a volume of .370cm^3. 2) density of copper at room temperature is 8.94 g/cm^3. multiplying .370cm^3 by 8.94g gives you a mass of 3.31 g. 3) use the molar mass of copper = 63.55g/mol and divide 3.31g by 63.55g to get your number of moles. (.0521 moles) 4) finally multiply your moles by avogadros number (6.022x10^23) you have 3.1 x10^22 atoms in your penny, with significant digits limited to 2 by the radius of the penny.

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