AP Net Ionic Equations

AP equations are found in the free response section of the AP test AP equations are found in the free response section of the AP test. You will have 3 equations following by a question about the reaction. The equations are of mixed types.

The sections is worth 15 points and is 10% of the free response grade The sections is worth 15 points and is 10% of the free response grade. Free response is 50% of the total AP test grade.

All AP equations “work. ” In each case, a reaction will occur All AP equations “work.” In each case, a reaction will occur. These equations need to be written in net ionic form. All spectator ions must be left out and all ions must be written in ionic form.

Answer 3 equations that must be balanced. Each equation is followed by a question. 1 pt for reactants, 2 points for products, and 1 pt for each question.

Strong Acids are: Exception: concentrated sulfuric acid-keep together because it really is 97% H2SO4 and 3% water in the jug. Strong Bases are:

Weak acids and bases keep together

All molecular substances and nonsoluble compounds must be written together (not ionized!).

Know your solubility rules!!! Ca(OH)2 and Sr(OH) 2 are moderately soluble and can be written together or as ions. Ba(OH)2 is soluble and Mg(OH)2 is insoluble. CaSO4 and SrSO4 are moderately soluble and can be written together or as ions. Weak electrolytes, such as acetic acid, are not ionized. Solids and pure liquids are written together, also. A saturated solution is written in ionic form while a suspension is written together.

Double Replacement Two compounds react to form two new compounds. No changes in oxidation numbers occur. All double replacement reactions must have a “driving force” that removes a pair of ions from solution.

Manganese(II) nitrate solution is mixed with a sodium hydroxide solution

Excess hydrochloric acid is added to an aqueous solution of potassium sulfite

Hydrogen sulfide gas is bubbled through a solution of lead(II) nitrate

A solution of ammonium sulfate is added to a potassium hydroxide solution

Solutions of tripotassium phosphate and zinc nitrate are mixed

Gaseous hydrofluoric acid reacts with solid silicon dioxide.

Single Replacement Rxns Treat like redox reactions. Reaction where one element displaces another in a compound. One element is oxidized and another is reduced. A + BC  B + AC + charges replace + and – charges replace -

Active metals replace less active metals or hydrogen from their compounds in aqueous solution.

Active nonmetals replace less active nonmetals from their compounds in aqueous solution. Each halogen will displace less electronegative (heavier) halogens from their binary salts.

Examples A piece of aluminum metal is added to a solution of silver nitrate

Small chunks of solid sodium are added to water

Chlorine gas is bubbled into a solution of sodium bromide

Magnesium turnings are added to a solution of iron(III) chloride

Anhydrides Anhydride means “without water.” Water is a reactant in each of these equations.

Memorize the Rules Look for: 1. Oxides + H2O a. metallic oxide + H2O  base b. nonmetallic oxide + H2O  acid

2. Metal hydride + H2O metal hydroxide + H2

3. Group 1 and 2 nitride + H2O metal hydroxide + NH3

4. Phosphorus halide + H2O  H3PO4 or H3PO3 + H(halide) acid

Examples Excess water is added to solid calcium hydride

Solid lithium hydride is added to water

Solid dinitrogen pentoxide is added to water

Solid potassium oxide is added to water

Phosphorus pentachloride solid is added to water

Methylamine gas is bubbled into distilled water

Oxidation-Reduction Reactions Redox reactions involve the transfer of electrons. The oxidation numbers of at least two elements must change. Single replacement, some combination and some decomposition reactions are redox reactions.

To predict the products of a redox reaction, look at the reagents given to see if there is both an oxidizing agent and a reducing agent. When a problem mentions an acidic or basic solution, it is probably redox.

Common oxidizing agent Product formed MnO4- in acidic solution Mn2+ MnO2 in acidic solution MnO4- in neutral or basic solution MnO2 (s) Cr2O72- in acidic solution Cr3+ HNO3, concentrated NO2 HNO3, dilute NO H2SO4, hot, concentrated SO2

Common oxidizing agent Product formed Metal-ic ions Metal-ous ions Free halogens Halide ions Na2O2 NaOH HClO4 Cl- H2O2 H2O

Common reducing agent Product formed Halide ions Free halogen Free metals Metal ions Sulfite ions or SO2 Sulfate ions Nitrite ions Nitrate ions

Common reducing agent Product formed Free halogens, dilute basic solution Hypohalite ions Free halogens, conc. basic solution Halate ions Metal-ous ions Metal-ic ions H2O2 O2 C2O42- CO2

Examples A solution of tin(II) chloride is added to an acidified solution of potassium permanganate.

Hydrogen peroxide solution is added to a solution of iron(II) sulfate

Potassium permanganate solution is added to a solution of oxalic acid acidified with a few drops of sulfuric acid.

A piece of iron is added to a solution of iron(III) sulfate.

Solid sodium dichromate is added to an acidified solution of sodium iodide

Potassium permanganate is mixed with an alkaline solution of sodium sulfite

Copper (II) sulfide is oxidized by dilute nitric acid.

A solution of potassium iodide is added to an acidified solution of potassium dichromate.

Acid-Base Neutralization Rxns Acids react with bases to produce water and salts.

Examples Hydrogen sulfide gas is bubbled through a solution of potassium hydroxide

A solution of sodium hydroxide is added to a solution of sodium dihydrogen phosphate until the same number of moles of each compound has been added

Nitric acid is added to crystals of pure calcium oxide

Carbon dioxide is bubbled through a solution of sodium hydroxide

Decomposition Reactions Reaction where a compound breaks down into two or more elements or compounds. Heat, electrolysis, or a catalyst is usually necessary.

Memorize the rules! 1. Metal Carbonate  Metal oxide + CO2 2. Metal Chlorate  Metal chloride + O2

3. Hydrogen peroxide water + oxygen 4. Ammonium carbonate ammonia + water + carbon dioxide 5. Sulfurous acid  Sulfur dioxide + water 6. Carbonic acid  carbon dioxide + water

Examples A solution of hydrogen peroxide is heated

Magnesium carbonate is heated

Potassium chlorate is heated in the presence of manganese dioxide

Solid ammonium carbonate is heated

Addition Reactions Two or more elements or compounds combine to form a single product.

Memorize the rules! Most of these should already look familiar. 1. 2 cmpds  form one compound 2. If excess use the higher oxidation number If limited use the lower oxidation number

3. Nonmetal oxide + water  acid 4. Metal oxide + water  base 5. Metal oxide + sulfur dioxide Metal sulfite 6. Metal oxide + carbon dioxide  metal carbonate

Examples Magnesium oxide is added to a container of carbon dioxide gas

Solid calcium oxide is heated in the presence of sulfur trioxide gas

Calcium metal is heated strongly in nitrogen gas

The gases boron trifluoride and ammonia are mixed

Combustion Reactions -Elements or compounds combine with oxygen.

Memorize these rules. Hydrocarbon + oxygen  carbon dioxide + water 2. ammonia + oxygen  NO + H2O if excess O2  NO2 + H2O

3. Nonmetal hydride + oxygen  nonmetal oxide+ water 4. Nonmetal sulfide+oxygen  nonmetal oxide + sulfur dioxide

Methane is burned in the presence of oxygen

Lithium metal is burned in air

Solid zinc sulfide is heated in an excess of oxygen

A piece of solid bismuth is heated strongly in oxygen

Complex Ion Reactions Complex ions are made up of a ____________ and a _____________. [Co(NH3)6]+3 is the complex ion NH3 is the ligand, Co is the metal

Possible metals: Cu/Zn/Ag/Cd/Fe/Al Possible ligands: NH3, OH-1, SCN-1 Magic number? Double charge to get magic number Exceptions to the trick: **[Al(OH)4]- **[Fe(SCN)]2+

Example: [Co(NH3)6] Cl3 NH3 is the ligand, [Co(NH3)6]+3 is the complex ion

Common complex ions on AP equations **[Al(OH)4]- tetrahydroxoaluminate ion formed from: (Al or Al(OH)3 or Al3+ + OH-) [Ag(NH3)2]+ diamminesilver(I) ion formed from (Ag+ + NH3)

[Zn(OH)4]2- tetrahydroxyzincate ion formed from (Zn(OH)2 + OH-) [Zn(NH3)4]2+ tetramminezinc ion formed from (Zn2+ + NH3) [Cu(NH3)4]2+ tetraminecopper(II) ion formed from (Cu2+ + NH3)

[Cd(NH3)4]2+ tetraminecadmium(II) ion formed from (Cd2+ + NH3) **[Fe(SCN)]2+ thiocyanairon(III) ion formed from (Fe3+ + SCN-) [Ag(CN)2]- dicyanoargentate(I) ion formed from (Ag+ and CN-)

Remember the following when writing complex ion reactions: Acid to complex ion  break it up 2. Acid to NH3 complex  NH4+ + breakup complex ion 3. HCl + Ag complex  AgCl + Breakup complex ion

Examples Concentrated (15M) ammonia is added in excess to a solution of copper (II) nitrate

Dilute hydrochloric acid is added to a solution of tetraminecopper (II) sulfate

A suspension of zinc hydroxide is treated with concentrated sodium hydroxide solution

Solid silver chloride is added to a concentrated solution of ammonia

Hydrochloric acid is added to a solution of dihydroxysilver bromide