8: Chapter 7 - Solutions
- Page ID
- 369969
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- 8.1: Homogenous Mixtures
- There are two types of mixtures: mixtures in which the substances are evenly mixed together (called a homogenous mixture, or solution) and a mixture in which the substances are not evenly mixed (called a heterogeneous mixture). When a solution, or homogenous mixture, is said to have uniform properties throughout, the definition is referring to properties at the particle level.
- 8.2: Solubility and Saturation
- Solutions can be formed in a variety of combinations using solids, liquids, and gases. We also know that solutions have constant composition and we can also vary this composition up to a point to maintain the homogeneous nature of the solution. Reasons for why solutions form will be explored in this section, along with a discussion of why water is used most frequently to dissolve substances of various types.
- 8.3: Gas Solubility
- Several factors affect the solubility of a given substance in a given solvent. Temperature is one such factor, with gas solubility typically decreasing as temperature increases. This is one of the major impacts resulting from the thermal pollution of natural bodies of water.
- 8.4: Mass Percents
- To define a solution precisely, we need to state its concentration: how much solute is dissolved in a certain amount of solvent. Words such as "dilute" or "concentrated" are used to describe solutions that have a little or a lot of dissolved solute, respectively. However "dilute" and "concentrated" are relative terms, and have meanings dependent on various factors. The mass/mass percent (% m/m) is defined as the mass of a solute divided by the mass of a solution times 100.
- 8.5: Molarity
- Another way of expressing concentration is to give the number of moles of solute per unit volume of solution. Of all the quantitative measures of concentration, molarity is the one used most frequently by chemists. Molarity is defined as the number of moles of solute per liter of solution. The symbol for molarity is MM or moles/liter. Chemists also use square brackets to indicate a reference to the molarity of a substance.
- 8.6: Dilutions
- We are often concerned with how much solute is dissolved in a given amount of solution. We will begin our discussion of solution concentration with two related and relative terms—dilute and concentrated.
- 8.7: Solution Stoichiometry (Titration)
- Double replacement reactions involve the reaction between ionic compounds in solution and, in the course of the reaction, the ions in the two reacting compounds are “switched” (they replace each other). Because these reactions occur in aqueous solution, we can use the concept of molarity to directly calculate the number of moles of reactants or products that will be formed, and hence their amounts (i.e. volume of solutions or mass of precipitates).