What mass of a 4.00% NaOH solution by mass contains 15.0 g of NaOH?.(a) Outline the steps necessary to answer the question. Consider this question: What mass of a concentrated solution of nitric acid (68.0% HNO 3 by mass) is needed to prepare 400.0 g of a 10.0% solution of HNO 3 by mass?.(credit a: modification of work by Jenn Durfey credit b: modification of work by “vastateparkstaff”/Wikimedia commons) (b) Inline water filters reduce the concentration of solutes in tap water. (a) In some areas, trace-level concentrations of contaminants can render unfiltered tap water unsafe for drinking and cooking. Inline water filters are designed to reduce the concentration of fluoride and several other trace-level contaminants in tap water ( Figure 3). For example, the EPA has identified the maximum safe level of fluoride ion in tap water to be 4 ppm. Concentrations of these contaminants are typically very low in treated and natural waters, and their levels cannot exceed relatively low concentration thresholds without causing adverse effects on health and wildlife. \textīoth ppm and ppb are convenient units for reporting the concentrations of pollutants and other trace contaminants in water. The mass percentage of a solution component is defined as the ratio of the component’s mass to the solution’s mass, expressed as a percentage: Percentages are also commonly used to express the composition of mixtures, including solutions.
Mass PercentageĮarlier in this chapter, we introduced percent composition as a measure of the relative amount of a given element in a compound. In this section, we will introduce some other units of concentration that are commonly used in various applications, either for convenience or by convention. However, molarity is only one measure of concentration. In the previous section, we introduced molarity, a very useful measurement unit for evaluating the concentration of solutions. Perform computations relating a solution’s concentration and its components’ volumes and/or masses using these units.Define the concentration units of mass percentage, volume percentage, mass-volume percentage, parts-per-million (ppm), and parts-per-billion (ppb).By the end of this section, you will be able to: