The discussion revolves around estimating the density of chromium ions in ruby, given a concentration of chromium at 0.05% by weight. Participants are examining the implications of this concentration on density calculations and addressing potential errors in the original poster's approach.
Some participants have pointed out discrepancies in the calculations related to the percentage of chromium, while others have confirmed the need for the atomic mass in the density estimation. There is an ongoing exploration of the calculations, with no clear consensus on the correct approach yet.
Participants are working under the assumption that the concentration of chromium is accurately stated as 0.05% by weight, and there is a focus on the implications of this assumption in the calculations. The decay rate mentioned appears to be unrelated to the primary problem.
But your calculation treated it as 5%.lcr2139 said:Yes, I really meant 0.05%.
haruspex said:But your calculation treated it as 5%.
I believe you will also need the atomic mass of chromium.
The 0.5*10-3 was quoted as a decay rate, with the right units for that, which has nothing to do with the problem. (In fact, lcr wrote 103, not 10-3., but minus seems more likely for a decay rate.)ChuckB said:0.5*10^-3 = .0005 which = .05%
lcr2139 treated it properly in the calculation (not to say that I have any idea what the calculation is, only that I know that 0.5*10^-3 = .05%)
lcr2139 said:density of ruby = 4.02 g/cm^3
density of chromium = (4.02)(0.05) = .201 g/cm^3
Your calculation looks right to me.lcr2139 said:density of ruby: 4.02 g/cm^3
molecular weight of chromium: 52 g/mol
(4.02g/cm^3)*(.0005)*(6.022*10^23 atoms/mol) / (52 g/mol) = 2.32*10^19 cm^-3
This is wrong! The real answer is NsubT= 1.6 * 10^19 cm^-3
where am I going wrong?