Clarification:
Density of Gold: 20 g/cm3
Density of Silver/Gold mix: 10g/cm3
How does one figure out if a crown is pure gold or a mix without melting the crown.
2007-06-16 13:14:33 · 5 answers · asked by archy 1 in Science & Mathematics ➔ Physics
Weigh the crown. Then do the Archimedes thing as answer 1 said, but disregard the rest of that answer. What Archimedes noted is that the water displaced by anything immersed in water is the volume (not the mass) of the object. You know the crown's weight and volume, so divide the weight by g to get its mass, then density = mass (g) / volume (cc).
2007-06-16 15:22:35 · answer #1 · answered by kirchwey 7 · 0⤊ 0⤋
Do what Archimedes did:
Fill a container to the brim with water, placing a tray underneath it which is deep enough to hold water.
Drop one crown into the bucket slowly, you will find that the water has been displaced. Remove the bucket, collect the water and weigh it using scales, record the mass.
Repeat with the second crown.
As Upthrust = Density of the crown x volume of the water displaced x gravitational constant and:
Weight = mass x gravitational constant
Weight = Upthrust therefore m = volume x density.
Hence the greater density crown (gold) will displace more water than the mixture (gold and silver). The crown with the heavier mass in water is the gold crown.
2007-06-16 13:24:57 · answer #2 · answered by Tsumego 5 · 0⤊ 0⤋
I believe the way the old assay offices worked was to weigh the ore first , and get an exact weight . Then they placed the ore in a carefully measured amount of water and measured how much water was displaced by the ore.
You then have a weight and a volume which can be calculated back to a specific value . Compare that with pure gold or a known alloy.
2007-06-16 13:27:44 · answer #3 · answered by mark 6 · 0⤊ 0⤋
Find the masses of crown when it is in air and when it is completely immersed in water.
Crown weighs less in water.
The apparent loss of mass in water divided by the density of water gives the volume of the crown.
The density of the material of the crown is, ‘mass of crown in air/ volume of crown’
The density found = 20gm /cm^3 if it is (pure) gold.
The density found < 20gm/cm^3 if silver is added.
2007-06-16 19:33:44 · answer #4 · answered by Pearlsawme 7 · 0⤊ 0⤋
Hmm... I would've thought there were public records available that listed dates when different alloys were used in minting. Is this a hypothetical?
If so, rather than get fancy, why not just use a basic streak test? Let the acid do the math...
2007-06-18 20:06:02 · answer #5 · answered by blackcatmining 1 · 0⤊ 0⤋