Chapter 4: Reactions in Aqueous Solutions Precipitation Reactions Acid/Base Reactions Oxidation/Reduction Reactions Solution Stoichiometry

Precipitation Reaction

Acid/Base Reactions - An acid is a molecular substance that ionizes to form a hydrogen ion (H+) and increases the concentration of aqueous H+ ions when it is dissolved in water. Because a hydrogen atom consists of a proton and an electron, H+ is simply a proton; therefore, an acid can also be thought of as a substance that can donate a proton. - A base is a substance that increases the concentration of aqueous OH– ions when it is dissolved in water. Bases can be either ionic or molecular substances. A base can be thought of as a substance that can accept a proton; in other words, bases are substances that react with H+ ions.

Ionization of Acids and Bases Ionization of a strong acid: Ionization of a Strong Base:

Oxidation – Reduction Reaction Oxidation is Loss of Electrons Reduction is Gain of Electrons A METAL SOLID WILL BE OXIDIZED BY THE IONS OF ANY METAL BELOW IT ON THE ACTIVITY SERIES!! :)‏

Solution Concentration The most commonly used expression of concentration is molarity. Symbolized with a capital M, molarity is the ratio of the number of moles of solute to the number of liters of solution. The amount of concentrated stock solution necessary to make up a given volume of the desired concentration is determined using the equation

Solution Stoichiometry Titration involves the carefully metered addition of a standard solution of one reactant to a flask containing an unknown quantity of the other reactant. The point in the titration at which stoichiometric amounts of reactants have been combined is called the equivalence point. For many reactions, the equivalence point is not an obvious occurrence, and so we add an indicator to the flask. An indicator is a compound that changes color at or very near the equivalence point. The point at which the indicator changes color is called the end point.