Aqueous Reactions and Solution Stoichiometry Chapter 4 Aqueous Reactions and Solution Stoichiometry

General Properties of Aqueous Solutions

Ionic Compounds in Water

Molecular Compounds in Water

Strong and Weak Electrolytes Simulation Electrolyte activity

Precipitation Reactions    

Solubility Guidelines

Double Displacement (Exchange) Reactions

Ionic Equations

Acid-Base Reactions Acids and Bases are also common electrolytes, which dissociate in water (soluble/separate) Acids are substances that ionize in aqueous solutions to form hydrogen ions (H+) thereby increasing the concentration of H+(aq) ions. Because hydrogen atoms consist of only one proton and one electron, is H+ simply one proton. Thus acids are often called proton donors. Just like the ionic compounds we have been studying, water also causes the H+(aq) ion to separate from its other half. Molecules of different acids can ionize to form different numbers of H+(aq) ions. Both HCl and HNO3 are monoprotic acids yeilding only one H+(aq) ion. H2SO4, however, is a diprotic acid that yields two H+(aq) ions. This occurs to two steps however.

Acid-Base Reactions cont. Bases are substances that accept (react with) H+(aq) ions. Bases produce hydroxide ions (OH-) when they dissolve in water. Ionic hydroxide compounds such as NaOH, KOH, and Ca(OH)2 are among the most common bases, separating just as the ions we have been studying separate. Compounds that do not contain OH- ions can also be bases. For example, ammonia is a common base that when added to water, it accepts an H+ from the water and thereby produces an OH- ion.

Strong and Weak Acids and Bases Acid and bases that completely dissociate in solution (strong electrolytes) are strong acids and bases. (pg 130 in AP Text) Those that only partially dissociate in solution (weak electrolytes) are weak acid and bases. Not only strong acids are highly reactive though… So strong electrolytes include all soluble ionic compounds and strong acids. Weak electrolytes include weak acids and bases.

Neutralization Reactions and Salts When a solution of a strong acid and strong base are mixed a neutralization reaction occurs because the H+ the acid combines with the OH- from the base to make water and a salt (ionic compound whose anion comes from an acid and whose cation comes from an base. HCl + NaOH H2O + NaCl Video simulation Also have net ionic equations… Sample Exercise 4.7 pg 133

Acid-Base Reactions with Gas Formation Many bases beside OH- react with H+ to for molecular compounds such as the sulfide ion and the carbonate ion. Both of these ions reaction with acids to form gases. See page 134 for net ionic equations. Net Ionic Equation

Oxidation-Reduction Reactions Reactions in which electrons are transferred between reactants-redox reactions Most are Single Displacement reactions. When an atom, ion or molecule has become more positively charged by losing electrons it is oxidized (oxidation). LEO When an atom, ion or molecule has become more negatively charged by gaining electrons, it is reduced (reduction). GER The oxidation of one substance is always accompanied by the reduction of another substance. As electrons are transferred between them. Calcium Water Demo on each table

Oxidation Numbers We need a system to keep track of whether electrons are lost or gained by a substance to determine if a redox reaction has taken place.

Oxidation of Metals by Acids and Salts

Activity Series of Metals

Concentrations of Solutions

Converting between Molarity, Moles and Volume

Dilutions

Solution Stoichiometry

Titrations