Determing whether or not something is truly gold?

rudi_in · Sep 7, 2006, 06:46 PM

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glamorousbride · Sep 7, 2006, 06:51 PM

I am in college. I am an elementary education major/english major, and accidently signed up for the wrong science class and it's too late to switch.

This is just part of a lab report that is to introduce the different measuring equiptment found in the lab.

The text I am using is [Physics, Laboratory Experiments]

My answer is: To determine if the crown is gold, I would have found it’s mass and volume and used that to find its density. I would compare my experimental density value with the accepted standard density of gold.

rudi_in · Sep 7, 2006, 06:53 PM

Bingo.

A crown with silver in it would not have a density equal to 19.3 g/cm^3

dmatos · Sep 7, 2006, 06:55 PM

Assuming that the crown must not be destroyed, and I had a reliable source of pure gold, I would compare the densities of the crown and the "known" gold. Use water displacement to find the volume of the crown, obtain an equal volume of pure gold, and weigh the two on an accurate balance scale.

Hmm. This appears to be very close to what Archimedes himself did:

http://math.nyu.edu/~crorres/Archime...Vitruvius.html

Nowadays, I'd just huck the thing under an SEM, and perform some EDX analysis on it. Electron Dispersive X-ray measures the wavelength of the photons emitted from excited particles. These wavelengths are directly related to energy levels, which are unique for each atom, thanks to quantum mechanics.

Determing whether or not something is truly gold?

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