fluoride ion in drinking water teeth against cavities. The target of the fluorid
ID: 1036880 • Letter: F
Question
fluoride ion in drinking water teeth against cavities. The target of the fluoridation is hydroxyapatite, Caio(PO4)6(OH)2, a compound in tooth enamel. There is concern, however, that fluoride ions in water may contribute to skeletal fluorosis, an arthritis-l disease. a. Write a net ionic equation for the reaction between ike hydroxyapatite and sodium fluoride that produces fAluorapatite, Ca1o(PO)&F2.; b. The U.S. EPA currently restricts the concentration of F in drinking water to 4 mg/L. Express this concentration of F in molarity. One study of skeletal fluorosis suggests that drinking water with a fluoride concentration of 4 mg/L for 20 years raises the fluoride content in bone to 6 mg/g, a level at which a patient may experience stiff joints and other symptoms. How much fluoride (in milligrams) is c. resent in a 100 mg sample of bone with this fluoride concentration?Explanation / Answer
a. Ca10(PO4)6(OH)2 + 2NaF ---> Ca10(PO4)6F2 + NaOH
b. atomic. wt. F- = 18.998 g/mol, so 4 mg/L = 0.004/18.998 = 0.0002105 M
c. Flouride concentration in bone = 6 mg/g, so in 100 mg of bone is 6/10 = 0.6 mg in 100 mg of bone.
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