A mixture contains only \(\mathrm{NaCl}\) and \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3} .\) A \(0.456-\mathrm{g}\) sample of the mixture is dissolved in water, and an excess of NaOH is added, producing a precipitate of \(\mathrm{Fe}(\mathrm{OH})_{3} .\) The precipitate is filtered, dried, and weighed. Its mass is 0.107 g. Calculate the following. a. the mass of iron in the sample b. the mass of \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}\) in the sample c. the mass percent of \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}\) in the sample

The mole concept is a fundamental principle in chemistry that helps us quantify the number of particles, such as atoms or molecules, in a given sample. A mole is defined as the amount of substance containing as many elementary entities (atoms, molecules, ions, etc.) as there are atoms in 12 grams of carbon-12. This number is known as Avogadro’s number and is approximately equal to \(6.022 \times 10^{23}\).

When it comes to chemical reactions and stoichiometry, the mole concept allows us to convert between the mass of a substance and the number of moles, providing a bridge between the macroscopic world we can measure and the microscopic world of atoms and molecules.For example, in the textbook exercise we examined, we converted the mass of iron (III) hydroxide precipitate to moles using the molar mass, which illustrates the practical application of the mole concept in solving real-world chemistry problems.

A chemical reaction is a process where reactants are transformed into products. Understanding chemical reactions involves recognizing how reactants are converted into products, usually via the breaking and forming of chemical bonds, and how the Law of Conservation of Mass applies. This law states that matter cannot be created or destroyed in a chemical reaction.

Using stoichiometry, we can use balanced chemical equations to relate the quantities of reactants and products. Stoichiometry is the quantitative relationship between the substances in a chemical reaction. The coefficients in the balanced chemical equation tell us the ratio in which reactants combine and products form. In the provided exercise, the stoichiometry between iron (III) nitrate and iron (III) hydroxide plays a crucial role in determining the mass and mass percent of iron (III) nitrate in the sample.

Molar mass is the mass of one mole of a substance (usually in grams per mole, g/mol) and is numerically equal to the substance’s relative atomic or molecular mass in atomic mass units (amu). Determining the molar mass of a compound involves adding the molar masses of the individual elements present in the formula, with their corresponding atomic molar masses and ratios considered.

Knowing the molar mass allows chemists to calculate the number of moles in a given sample of a substance (and vice versa) by dividing the sample mass by the molar mass. For instance, in calculating the mass of iron (III) nitrate from the mass of iron (III) hydroxide in the problem solution, the molar masses of both compounds were essential. Without accurate molar masses, our stoichiometric calculations would be incorrect, showing the critical role molar mass plays in quantifying aspects of a chemical reaction.