A toothpaste contains 0.228% by mass sodium fluoride used to prevent dental cari

Question

A toothpaste contains 0.228% by mass sodium fluoride used to prevent dental caries and 0.31% by mass triclosan C12H7Cl3O2, an antigingivities agent. One tube contains 119 g of toothpaste. (Express answer using 3 significant figures)
1. How many moles of NaF aew in the tube of toothpaste? 2. How many fluoride ions, F-, are in the tube of toothpaste? 3. How many grams of sodium ion, Na+, are in 2.45 g of toothpaste? 4. How many molecules of triclosan are in the tube of toothpaste? A toothpaste contains 0.228% by mass sodium fluoride used to prevent dental caries and 0.31% by mass triclosan C12H7Cl3O2, an antigingivities agent. One tube contains 119 g of toothpaste. (Express answer using 3 significant figures)
1. How many moles of NaF aew in the tube of toothpaste? 2. How many fluoride ions, F-, are in the tube of toothpaste? 3. How many grams of sodium ion, Na+, are in 2.45 g of toothpaste? 4. How many molecules of triclosan are in the tube of toothpaste?
1. How many moles of NaF aew in the tube of toothpaste? 1. How many moles of NaF aew in the tube of toothpaste? 2. How many fluoride ions, F-, are in the tube of toothpaste? 3. How many grams of sodium ion, Na+, are in 2.45 g of toothpaste? 4. How many molecules of triclosan are in the tube of toothpaste?

Explanation / Answer

Q1

moles of NaF in toothpaste

mass of NaF = 0.228/100*119 = 0.27132 g of NaF

mol = mass/MW = 0.27132/41.98817248

mol of NaF = 0.006461

Q2.

1 mol of F- per 1 mol of NaF

0.006461 mol of NaF = 0.006461 mol of F-

Q3

mass of Na+ in 2.45 g

mol of NaF in 119 g --> 0.006461

mol of NaF in 2.45 --> 2.45/119*0.006461 = 0.0001330 mol of NaF

mol of Na in NaF = 1:1 ratio

0.0001330 mol of Na+

mass = mol*MW = 0.0001330*23 = 0.003059 g = 3.059 mg

Q4

triclosan in tube

mass = 0.31/199*119 = 0.18537 g of C12H7Cl3O2

mol = mass/MW = 0.18537/289.5418 = 0.0006402 mol

1 mol = 6.022*10^23

molecules= (0.0006402)(6.022*10^23) = 3.8552*10^20 molecules

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