10/15/2017 11:55 PM 71.8/100 10/11/2017 02:45 PM core Print l Calou atorPeriodic
ID: 539890 • Letter: 1
Question
10/15/2017 11:55 PM 71.8/100 10/11/2017 02:45 PM core Print l Calou atorPeriodic Table Question 5 of 11 Sapling Learning To aid in the prevention of tooth decay, it is recommended that drinking water contain 0 700 ppm AurdeF) (a) How many grams of F" must be added to a cylindrical water reservoir having a diameter of 3.29 x102 m and a depth of 15.56 m? Number 8 F Number ) How many grams of sodium NaF, contain this much D g NaF fuoride? O Prevous Give Up & View Soldon Check Answer Next Ext o search DOLL F7 Fe F9 F6 F3 F4F5 F1 F2Explanation / Answer
Solution-
a) Volume of solution = volume of reservoir
= x (diameter/2)2 x depth
= 3.14 x (3.29 x 10^2/2)^2 x 15.56
= 1.32 x 10^6 m3 = 1.32 x 10^12 mL
Let us assume that density of solution = density of water = 1.00 g/mL
Mass of solution = volume x density
= 1.000 x 10^13 x 1.00 = 1.000 x 10^13 g
Concentration of F- in ppm = mass of F-/mass of solution x 10^6
Mass of F- = concentration of F- in ppm x mass of solution/10^6
= 0.70 x 1.000 x 10^13/10^6
= 7.0 x 10^6 g
(b) NaF => Na+ + F-
Moles of NaF = moles of F- = mass of F-/molar mass of F-
= 7.0 x 10^6/19.00 = 3.68 x 10^5 mol
Mass of NaF = moles of NaF x molar mass of NaF
= 3.68 x 10^5 x 41.99
= 1.54 x 10^7
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.