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"ASG2216 Assignment09 5-figure 07 gif 418x5. x eChegg Study Guided e VASG2216 Assignmen e VASG22 16 Assig T09 × e chemistry question c × e Europiumis A Lanthan × × × C www.webassign.net/web/Student/Assignment-Responses/submit?dep-14204280 5. 3/6 points | Previous Answers My Notes+Ask Your Teacher Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca 10(PO4)6(OH)2. Trace elements in teeth of archaeological specimens provide anthropologist with clues about diet and diseases of ancient people. Students at Hamline University measured strontium in enamel from extracted wisdom teeth by atomic absorption spectroscopy. Solutions with a constant total volume of 10.0 mL contained 0.740 mg of dissolved tooth enamel plus variable concentrations of added Sr. Added Sn (ng/mL = ppb) 0 2.50 5.00 7.50 10.00 Signal (arbitrary units) 28.0 34.3 42.8 51.5 58.6 (a) Find the concentration of Sr in the 10 mL sample solution in parts per billion = ng/mL. 4.0 18.72 ppb (b) Find the concentration of Sr in tooth enamel in parts per million 4.0 g/g 115.19 Xppm 6. 3/10 points | Previous Answers My Notes Ask Your Teacher Europium is a lanthanide element found at parts per billion levels in natural waters. It can be measured from the intensity of orange light emitted when a solution is illuminated with ultraviolet radiation. Certain organic compounds that bind Eu(III) are required to enhance the emission. The figure below shows standard addition 12:12 AM Ask me anything 11/8/2016 2

Explanation / Answer

Concentration of Sr in the solution = 8.72 ppb = 8.72 ug/mL

Mass of Sr in the solution = (8.72 ug/mL x 10 mL) = 87.2 ug

Mass of dissolved tooth enamel = 0.740 mg = 0.00074 g

Concentration of Sr in the solution = 87.2 ug / 0.00074g = 1.17 x10^5 ppm

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