Chapter 4: Reactions in Aqueous Solutions

A solution is a homogenous mixture of 2 or more substances The solute is(are) the substance(s) present in the smaller amount(s) The solvent is the substance present in the larger amount In aqueous solutions (aq) *solvent is water *solute can be ionic compounds, aqueous acids, bases, or molecular compounds 4.1

An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity. So Gatorade is just glorified salt water… A nonelectrolyte is a substance that, when dissolved, results in a solution that does not conduct electricity. nonelectrolyte weak electrolyte strong electrolyte 4.1

4 Types of Inorganic Compounds Molecular; Made of 2 or more Nonmetals Ionic; Made of + and – ion. Generally + ion is from metal and – ion from nonmetal. Bases; + ion; - ion is hydroxide (OH)- Aqueous Acid; H+ and – ion dissolved in water. Generally – ion is nonmetal

Inorganic Compounds Dissolved in Water ALL BUT MOLECULAR PRODUCE IONS Ionic Compounds Na Cl (aq) 2. Bases Na (OH) (aq) Na+ Cl- (OH)- Na+ 3. Aqueous Acids HCl (aq) 4. Molecular ICl (aq) NO Ions! Cl- H+ I Cl

Strong Electrolyte Weak Electrolyte Nonelectrolyte Strong Acids Weak Acids Molecular Compounds Strong Bases Weak Bases Ionic Compounds 4.1

Electrolytic Solutions Contain Mobile Cations (+) and Anions(-) Ionic Compounds, Aqueous Acids, and Base Dissociate Into the Ions They are Made of When Dissolved in Water. NaCl (s)  Na+ (aq) + Cl-(aq) More Ions in Solutions; Stronger Electrolyte H2O

Weak vs. Strong Electrolyte A strong electrolyte will produce more ions when same amount of solid is dissolved in solvent. H+ Cl- Strong Electrolyte – 100% dissociation HCl (g) H+ (aq) + Cl- (aq) H2O Weak Electrolyte – not completely dissociated HNO2 NO2- (aq) + H+ (aq) H2O NO2- H+ NO2- H+

Precipitation Reactions Mix two aqueous solutions made by dissolving ionic compounds in water. If a reaction happens, a precipitate (solid) is formed.

Predicting Products of Precipitation Reactions Ionic Compounds are Strong Electrolytes –Determine charge on all ions of reactants Using Ion Charges; Predict formula of products. ( + ion of one reactant forms compound with – ion of other reactant) Balance Equation Determine is product is solid or aqueous solution

Solubility Rules for Common Ionic Compounds In water at 250C Soluble Compounds Exceptions Compounds containing alkali metal ions and NH4+ NO3-, HCO3-, ClO3- Cl-, Br-, I- Halides of Ag+, Hg22+, Pb2+ SO42- Sulfates of Ag+, Ca2+, Sr2+, Ba2+, Hg2+, Pb2+ Insoluble Compounds CO32-, PO43-, CrO42-, S2- OH- Compounds containing alkali metal ions and Ba2+ 4.2

Predicting Products of Precipitation Reactions (Cont) Determine spectator ions (Ions that are still dissolved in water in the product) Write net ionic equation (Only shows ions involved in forming solid) Same as double replacement reactions from last year  just adding ONE extra step to it.

Precipitation Reactions Precipitate – insoluble solid that separates from solution PbI2 precipitate Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq) molecular equation Pb2+ + 2NO3- + 2Na+ + 2I- PbI2 (s) + 2Na+ + 2NO3- ionic equation Pb2+ + 2I- PbI2 (s) net ionic equation Na+ and NO3- are spectator ions 4.2

AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Write the net ionic equation for the reaction of silver nitrate with sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Ag+ + NO3- + Na+ + Cl- AgCl (s) + Na+ + NO3- Ag+ + Cl- AgCl (s) 4.2

Acids Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid. React with certain metals to produce hydrogen gas. React with carbonates and bicarbonates to produce carbon dioxide gas Bases Have a bitter taste. Feel slippery. Many soaps contain bases. 4.3

Bronsted Acids Produce H+ (proton) or (H3O)+ when dissolved in water Proton donor HNO3 (aq)  H+ (aq) + (NO3)- (aq) H2O HNO3 (aq) + H2O (l)  H3O+ (aq) + (NO3)- (aq)

Monoprotic acids; Produce one H+ when dissolved in water HNO3 H+ + NO3- Strong electrolyte, strong acid Diprotic acids; Produce two H+ when dissolved in water H2SO4 2 H+ + SO4-2 Strong electrolyte, strong acid Triprotic acids; Produce three H+ when dissolved in water H3PO4 3 H+ + PO4-3 Weak electrolyte, weak acid 4.3

Bronsted Bases Produce (OH)- when dissolved in water Proton (H+) acceptor Na(OH) (s) -----> Na+ (aq) + (OH)- (aq) H2O F- (aq) + H2O (l) <-> HF (aq) + (OH)- (aq)

Neutralization Reaction Acid + Base -> Salt + H2O

Practice Problem What is the neutralization reaction of hydrochloric acid and sodium hydroxide? HCl + NaOH  Must be a salt and water! Products: H2O + NaCl Simple double replacement reaction! HCl + NaOH  H2O + NaCl