Calculate the mass of \(\mathrm{NaCl}\) in a \(35-\mathrm{mL}\) sample of a \(1.3 \mathrm{M}\) NaCl solution.

Molarity is a measure of the concentration of a solute in a solution, and it is one of the most common units used in chemistry for this purpose. It is expressed as the number of moles of solute per liter of solution, often abbreviated as moles per liter (mol/L) or simply M. One mole of a substance is defined as the amount containing the same number of entities (atoms, molecules, ions, etc.) as there are atoms in 12 grams of carbon-12.

When you know the molarity of a solution, you have powerful information at your disposal. You can easily calculate how much of a substance is present in a given volume of solution, as in our example exercise requiring us to calculate the mass of NaCl in a 35-mL sample of a 1.3 M NaCl solution. This step involves simple multiplication of the solution's volume by its molarity to first determine the number of moles present.

Solution concentration refers to the amount of solute that is dissolved in a specific amount of solvent. Understanding the concentration is crucial for a myriad of applications including biological processes, chemical reactions, and even cooking recipes.

There are various ways to express concentration, with molarity being just one of them. Others include molality, normality, and mass percentage. Molarity is favored in many chemical calculations because it directly relates to the volume of the solution, which is easy to measure. In our textbook exercise, the molarity gives a clear indication of how concentrated the NaCl solution is, and from there, we can figure out the mass of the solute within a specific volume by translating moles into grams with the help of molar mass.

The molar mass is the mass of one mole of a given substance and is typically expressed in grams per mole (g/mol). Molar mass is a fundamental concept in chemistry as it bridges the gap between the microscopic scale of atoms and molecules and the macroscopic world we can measure and observe.

The molar mass of a compound like NaCl is calculated by adding together the molar masses of its constituent elements. For example, the molar mass of NaCl is derived from the sum of the molar mass of sodium (Na, approximately 22.99 g/mol) and the molar mass of chlorine (Cl, approximately 35.45 g/mol), resulting in a molar mass of approximately 58.44 g/mol. This allows us to convert between moles and grams, a necessary step in many stoichiometric calculations, including finding the mass of NaCl in our sample solution.