Chemistry: A toothpaste contains 0.254 % by mass sodium fluoride used to prevent dental caries and 4.4 % by mass KNO3, which decreases pain sensitivity. One tube contains 119 g of toothpaste. Part A How many moles of NaF are in the tube of toothpaste? Express your answer using three significant figures. Part B How many fluoride ions, F−, are in the tube of toothpaste? Express your answer using three significant figures. Part C How many grams of sodium ion, Na+, are in 1.35 g of toothpaste? Express your answer

sory l Don t know dis question...

A toothpaste contains 0.254 % by mass sodium fluoride

hervinlouis014

20.01.2022

A. 7,20x10⁻³mol NaF

B. 4,33x10²¹ F⁻ ions

C. 1,88x10⁻³g Na⁺

D. 3,1x10²² formula units

E. 132,08g/mol

F. 15,9g of CHCl₃; 0,293 mol of CHCl₃

Explanation:

A. 119g × (0,254% / 100) = 0,302g of NaF × (1mol / 41,99g) = 7,20x10⁻³mol NaF

B. 7,20x10⁻³mol NaF ≡ 7,20x10⁻³mol F⁻ × (6,022x10²³ ions / mol) = 4,33x10²¹ F⁻ ions

C. 1,35g × (0,254% / 100) = 0,00343g of NaF × (22,99g Na⁺ / 41,99g NaF) = 1,88x10⁻³g Na⁺

D. 119g × (4,4% / 100) = 5,236g of KNO₃ × (1mol / 101,1g) = 0,0518mol × (6,022x10²³ F.U / 1mol) = 3,1x10²² formula units

E. Formula of ammonium sulfate is (NH₄)₂SO₄. Molar mass is obtained thus:

N: 2N×(14g/mol) = 28g/mol

H: 8H×(1,01g/mol) = 8,08g/mol

S: 1S×(32g/mol) = 32g/mol

O: 4O×(16g/mol) = 64g/mol

Molar mass: 28 + 8,08 + 32 + 64 = 132,08g/mol

F. Molar mass of chloroform is 119,38g/mol, thus:

0,133 mol × (119,38g/mol) = 15,9g of CHCl₃

35,0g × (1mol / 119,38g) = 0,293mol of CHCl₃

I hope it helps!

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