I\'m kinda lost, please shoew work and explain? Fluoridation is the process of a

Question

I'm kinda lost, please shoew work and explain?

Fluoridation is the process of adding fluorine compounds to drinking water to help fight tooth decay. A concentration of 1 ppm of fluorine is sufficient for the purpose (1 ppm means one part per million, or 1 g of fluorine per 1 million g of water). The compound normally chosen for fluoridation is sodium fluoride, which is also added to some toothpastes. Calculate the quantity of sodium fluoride in kilograms needed per year for a city of 50,000 people if the daily consumption of water per person is 185.0 gallons. (Sodium fluoride is 45.0 percent fluorine by mass. 1 gallon = 3.785 L: 1 ton = 2000 lb: 1 lb = 453.6 g: density of water = 1.0 g/mL) Enter your answer in scientific notation. times 10 kilograms

Explanation / Answer

Find NaF in kg required per year for

n = 50000

V = 185 gal/person

Total V = 50000*185 = 9250000 gal /day --> 9250000 gal / day * 365 day / year = 3376250000 gal/year

change to L --> 3376250000 gal * 3.785 = 12779106250 L / year

now...

calculate

C = mass/V

V = 12779106250 Liters = 12779106250 kg = 12779106250000 g of water

C = 1 ppm = 1 g of F- / 10^6 g of water

so...

mass = C*V = (12779106250000 )(1/(10^6) = 12779106.25 g of F required

mol of F = mass/MW = 12779106.25/18.998403 = 672641.076726 mol o F

1 mol of F- = 1 mol of NaF

672641.076726 mol -> 672641.076726 mol of NaF

mass = mol*MW = 672641.076726*41.98817 = 28242967.8786 g of NaF

kg of NaF = 28242967.8786/1000 = 28242.96 kg of NaF

change to Scientific Notation = 2.82*10^4 kg of NaF

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