What mass of HCl is contained in 45.0 mL of an aqueous HCl solution that has a density of \(1.19 \mathrm{g} \mathrm{cm}^{-3}\) and contains 37.21\% HCl by mass?

Solution density is an essential concept in chemistry that describes the mass of a solution per unit volume. It's usually presented in grams per cubic centimeter (g/cm³). Understanding solution density is pivotal as it helps in determining the mass of a solution from its volume, which is a necessary step in various laboratory and industrial processes.

In the context of the example exercise, the density of the HCl solution is given as 1.19 g/cm³. Knowing the density, one can calculate the total mass of any volume of this solution. In practical terms, the high density of this HCl solution suggests it is quite concentrated, which is confirmed by the significant mass percentage of HCl present (37.21%).

When dealing with these calculations, remember that densities can vary with temperature and concentration, so ensure that you are using the correct values for your specific conditions.

Mass-volume calculation is a fundamental skill in chemistry that allows us to relate the mass of a substance to its volume through density. This computation is vital for preparing solutions and for stoichiometric calculations in reactions. To find the mass from volume and density, you can use the formula: \( \text{mass} = \text{density} \times \text{volume} \).

Using the exercise as an example, the volume of the solution is 45.0 mL (which is equal to 45.0 cm³ since 1 mL = 1 cm³). To find the total mass of the HCl solution, we multiply the given density (1.19 g/cm³) by this volume, yielding a mass that allows us to then find the mass of just the HCl using its percentage composition.

This process is a powerful tool in chemistry, giving us insight into the amount of reactant in a solution without necessitating the separation of the individual components, which can often be practically challenging or even impossible.

Chemistry stoichiometry refers to the quantitative relationship between reactants and products in a chemical reaction. It involves the use of balanced equations to calculate the precise amounts of substances consumed and produced. Percent composition by mass is a stoichiometric concept that indicates what portion of a compound's total mass is made up by a particular element or constituent.

In our exercise, we deal with the stoichiometry of a solution rather than a reaction, using percent composition to find the mass of HCl in an HCl solution. Once the total mass of the solution is known, we can multiply it by the percent composition of HCl (37.21%) to find the mass of just the HCl. Remember to convert the percentage to a decimal by dividing by 100 before multiplying.

Understanding stoichiometry is critical for predicting the outcomes of chemical reactions and for scaling up reactions from a laboratory to an industrial scale, ensuring that the proportions of reactants are correct to avoid waste and maximize yield.