Homework question?

Colmanite [Ca2B6O11 * 5 H20] is a salt whose boron content gives glass high clarity. You are a buyer for an optical fiber manufacturer and want pure material. You have just received a Certificate of Analysis for a lot that is 12.8 +- 1.2% (i.e;11.6 to 14.0%) by weight of boron. Would you buy it? (Show work of both problems)

%B = (6*atomic mass B)/(molar mass Ca2B6O11.5H2O)]*100 = ?

The way I see it you don't have two problems. The above calculates the percent B for a pure sample of the mineral. Something like 15.78% B. I wouldn't buy it.

To determine whether you should buy the Colmanite lot based on its boron content, you will need to calculate the range of boron content and compare it to your required purity level.

Let's start by calculating the range of boron content based on the given percentage range of 12.8 +- 1.2% (i.e., 11.6 to 14.0%).

Step 1: Calculate the lower limit of boron content:
Lower Limit = 12.8% - 1.2%
Lower Limit = 12.8% - (1.2/100) * 12.8%
Lower Limit = 12.8% - 0.1536%
Lower Limit = 12.6464%

Step 2: Calculate the upper limit of boron content:
Upper Limit = 12.8% + 1.2%
Upper Limit = 12.8% + (1.2/100) * 12.8%
Upper Limit = 12.8% + 0.1536%
Upper Limit = 12.9536%

So, the range of boron content for the Colmanite lot is 12.6464% to 12.9536%.

To determine whether you should buy the lot, you need to compare the range of boron content to your required purity level. If your required purity level is within this range, it is acceptable. However, if your required purity level falls outside this range, it is not suitable for your needs.

Therefore, based on the given information and calculations, you need to analyze whether your required purity level falls within the range calculated for the Colmanite lot.