The American Dental Association recommends that an adult female should consume 3.0 \(\mathrm{mg}\) of fluoride \(\left(\mathrm{F}^{-}\right)\) per day to prevent tooth decay. If the fluoride is consumed in the form of sodium fluoride \((45.24 \% \mathrm{F})\) , what amount of sodium fluoride contains the recommended amount of fluoride?

Understanding mass percentage is critical in chemistry, especially when dealing with solutions and mixtures. It simply tells us how much of a certain substance is present in a mixture as a percentage of the total mass. In our example, sodium fluoride (NaF) contains 45.24% of fluoride (F), which indicates that for every 100 grams of sodium fluoride, there are 45.24 grams of fluoride.

To calculate the mass percentage, you can use the formula: \(\text{Mass percentage} = \frac{\text{mass of component}}{\text{total mass of the mixture}} \times 100\).

When the exercise asks for the amount of sodium fluoride needed to obtain a specific amount of fluoride, the calculation involves using the mass percentage to establish a proportional relationship. In practice, this problem is solved by setting up a proportion based on the given mass percentage, followed by cross-multiplication to find the unknown quantity.

The molar mass of a substance is the mass of one mole of its particles, typically expressed in grams per mole (g/mol). It’s a fundamental concept when working with stoichiometry because it bridges the gap between the macroscopic scale (grams) and the microscopic scale (number of atoms, molecules, or ions).

To find the molar mass, you sum the atomic masses of all the atoms in a formula unit of the substance. For example, sodium fluoride (NaF) has a molar mass that is the sum of the molar mass of sodium (Na) and fluorine (F).

In stoichiometric calculations, once you determine the molar mass, you can convert between mass and moles of a substance, which is essential for determining how much of one compound reacts with a given amount of another compound, or in this case, how much sodium fluoride is needed to provide the recommended fluoride intake.

The chemical composition of a substance denotes what it's made of—the types and amounts of atoms in a molecule. Knowing the chemical composition allows chemists to predict how substances will react with one another. It is also essential for calculating stoichiometry problems, like determining the amount of an element within a compound or the required amounts of reactants for a chemical reaction.

In the context of the exercise, the chemical composition of sodium fluoride is one atom of sodium (Na) and one atom of fluorine (F). This simple ratio makes it straightforward to understand that the mass of fluoride in sodium fluoride contributes to 45.24% of the total mass of sodium fluoride. This percentage is key for calculating how much NaF is needed to provide a specific dose of fluoride, which is directly related to its chemical composition.