In the video, the water level was 15 milliliters before adding the chain, and 20 milliliters after adding the chain. When I weighed the chain, its mass was 72.5 grams.

Question

I believe the chain is solid metal (not gold plated), but is probably a blend of gold and other metals. I looked up that gold has a density of 19.3 g/ml, while the other metals like silver and copper usually blended with gold have a combined density of about 9.7 g/ml.

Determine what percentage of the chain is gold, by mass, to at least 1 decimal place?

Answer 1

The density of the chain is 72.5 / 5 or 14,5 g/ml

g represents the percent of gold

19.3g + 9.7(1 - g) = 14.5

19.3g + 9.7 - 9.7g = 14.5

9.6g = 4.8

g = 0.50

The alloy is 50% gold

Answer 2

The volume of the chain is

20 ml - 15 ml = 5 ml = 5 c.c.

The density of the chain is

72.5 g / 5 cc = 14.5 g/ cm3.

Well, we need more information to see what percent is gold. There is no other metal density given, so we need to stop here.