Deal with Colgate toothpaste, listed as having 0.16% w/v fluoride ion. 1. What i

Question

Deal with Colgate toothpaste, listed as having 0.16% w/v fluoride ion.

1. What is the concentration of fluoride ion in ppm?

2. What is the molarity of fluoride ion in the solution?

3. The compound used to obtain this fluoride concentration is sodium fluoride. How many grams of sodium fluoride would you have to add to a large (181 mL) tube of toothpaste to get the above listed fluoride concentration?

4 . The LDL0 (lowest reported lethal dose) for sodium fluoride is 75 mg/kg. How much toothpaste must a 12 kg toddler eat to achieve this dose?

5. A 1.000 L container is filled with an unknown gas at 20.0 C and 742 torr. The gas in the container is found to have a mass of 2.3243 grams. What is the MW of the gas?

Explanation / Answer

ANSWER

Dear candidte here we solve first question with all four parts. Please send the other one separately, as per guidelines one question one time.

Q1. The flouride content is 0.16%. It means 0.16 parts are present in 100 parts of the past.

One part of flouride will be present in 0.16 / 100 parts of past.

Therefore concentration in ppm = (0.16 / 100) X 106 = 1600 ppm

Q2. Molarity of flouride ion = (No. of moles of flouride ions / volume in liters)

No. of moles = mass of flouride ion / molar mass of flouride ion = 0.16 / 19.0 = 0.008 moles

0.008 Moles of flouride ion is present in 100mL of of the past

100mL = 100 / 1000 = 0.1L

Molarity of flouride ion = 0.008 / 0.1 = 0.08M

Q3. NaF -------> Na++ F-

One mole of NaF gives one mole of flouride ion. Therefore 0.08 M of NaF will give 0.08 M flouride.

Volume of tube = 181mL = 181 / 1000 = 0.181L

Molar mass of NaF = 42.0g

Molarity = No. of moles of NaF / Volue in liters

No. of moles of NaF = mass of NaF / Molar mass (42.0)

0.08 = mass of NaF / 42.0 X 0.181

mass of NaF = 0.6g.

Q4. LDL0 = 75mg/Kg

Mass of baby = 12Kg

Hence LDL0 for the baby = 12 X 75 = 900mg = 0.9g

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