You work as a geologist, studying the makeup of an unusual sample of colemanite,

Question

You work as a geologist, studying the makeup of an unusual sample of colemanite, an ore of boron with the formula Ca_2B_6O_11. This sample has unusually high percentages of boron-10, an isotope used experimental therapy for brain cancer. In order to be economically viable, your boss wants there to be at least 25% atom abundance of the isotope in the sample. You treat 10.000 g of colemite with excess sulfuric acid and determine that the sample contained 0.03119 moles of the mineral (Ca_2B_6O_11). Assuming normal molar masses for all other elements, will the sample be an economically viable source of^10B? What is the isotope abundance of boron-10 in the sample?

Explanation / Answer

Given 0.03119 moles of coelamite Ca2B6O11 in 10 g of coelamite Ca2B6O11

so there will be 6*0.03119 = 0.18714 moles of B-10 will be present

atomic mass of B-10 = 10 g/mol

so mass of B-10 present = 0.18714 * 10 = 1.8714 g

hence 1.8174 g of B-10 will be present in 10 g of mineral which is less than 25 % (2.5 g)

atom abundance = 1.8174 /10 * 100 % = 18.714 %

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