Fluoride is added to municipal drinking water supplies to protect teeth against
ID: 498341 • Letter: F
Question
Fluoride is added to municipal drinking water supplies to protect teeth against cavities. There is concern however that fluoride ions in water may contribute to skeletal fluorosis, arthritis-like disease. The typical concentration of fluoride in drinking water supplies is 1ppm. One study of skeletal fluorosis suggests that drinking water with a fluoride concentration of 2.1 times 10^-4 M for 20 years raises the fluoride content in bone to 6mg/g, a level at which a patient may experience stiff joints and other symptoms. How much fluoride (in milligrams) is present in a 115mg sample of bone with this fluoride concentration?Explanation / Answer
SOLUTION:
Flouride concentration in bones with stiffness = 6mg/g
It means 1g (or 1000mg) of bone contain 6mg of flouride
Hence 1mg of bone will contain 6 / 1000 = 0.006mg of flouride ion.
Therefore 115mg sample of bone will contain 115 X 0.006 = 0.69mg of flouride.