Equation Writing ReviewEquation Writing Review

Complexes and PPT’sComplexes and PPT’s

Acid-BaseAcid-Base

RedoxRedox

MiscellaneousMiscellaneous

AP Eq’n Writing DirectionsAP Eq’n Writing Directions

Write the formulas to show the reactants and the Write the formulas to show the reactants and the products for the three laboratory situations described products for the three laboratory situations described below.below.

In all cases, a reaction occurs.In all cases, a reaction occurs. Assume that solutions are aqueous unless otherwise Assume that solutions are aqueous unless otherwise

indicated.indicated. Represent substances in solution as ions if the Represent substances in solution as ions if the

substances are extensively ionized.substances are extensively ionized.• Strong acids and ionic compounds are extensively ionizedStrong acids and ionic compounds are extensively ionized• Not dissolved means no ions!Not dissolved means no ions!

Directions (continued)Directions (continued) Omit formulas for any ions that are unchanged Omit formulas for any ions that are unchanged

by the reaction.by the reaction.• Leave out spectatorsLeave out spectators• Words like Words like solid, liquid, gas, suspension, powdered, solid, liquid, gas, suspension, powdered,

piece of, strippiece of, strip, etc… mean , etc… mean no spectatorsno spectators• One point penalty per reaction for showing spectatorsOne point penalty per reaction for showing spectators

You must balance the equation.You must balance the equation.

Grading Equation WritingGrading Equation Writing

1 point for correct reactant formula(s)1 point for correct reactant formula(s) 2 points for correct product formula(s)2 points for correct product formula(s) 1 point for balancing1 point for balancing 1 point for answering simple related question1 point for answering simple related question -1 for including spectators-1 for including spectators

There are often multiple acceptable product There are often multiple acceptable product predictionspredictions

Miscellaneous Equations - OrganicMiscellaneous Equations - Organic

OrganicOrganic• CombustionCombustion

Red flag is “burned”Red flag is “burned” Form oxides (COForm oxides (CO22, H, H22O, …)O, …) CSCS22 + O + O22 ---> CO ---> CO22 + SO + SO22 (or SO (or SO33))

• Organic basesOrganic bases Methylamine = CHMethylamine = CH33NHNH2 2 ---> CH---> CH33NHNH33

++ = methylammonium = methylammonium Ethylamine =Ethylamine = CC22HH55NHNH22

• Dehydration synthesis: Can one lose H, the other OH?Dehydration synthesis: Can one lose H, the other OH? Review basic organic families and their structuresReview basic organic families and their structures

Misc. Equations - SynthesisMisc. Equations - Synthesis

Putting two pieces togetherPutting two pieces together The only possibility in reactions between two elementsThe only possibility in reactions between two elements

• PP44 + O + O22 ---> P ---> P22OO55

• Know strange allotropes?Know strange allotropes? PP44, S, S88, diatomics, diatomics

• Criss-cross valences to get a reasonable productCriss-cross valences to get a reasonable product Good option for non-aq rxns of elem + cmpdGood option for non-aq rxns of elem + cmpd

• NaS + ONaS + O22 ---> NaSO ---> NaSO33 (or similar) (or similar)

Occasionally for non-aq rxn of two compoundsOccasionally for non-aq rxn of two compounds• CaO + COCaO + CO22 ---> CaCO ---> CaCO33

Misc. Equations - DecompositionMisc. Equations - Decomposition

When a single compound is heated, you must break it When a single compound is heated, you must break it up into smaller piecesup into smaller pieces

These can be a bit diceyThese can be a bit dicey• make common products: water, COmake common products: water, CO2 2

• avoid elements (requires redox)avoid elements (requires redox) Make 2 or 3 reasonable common products Make 2 or 3 reasonable common products

• Frequently gasesFrequently gases

• Carbonates ---> oxide + COCarbonates ---> oxide + CO22 Criss-cross to get formula of oxideCriss-cross to get formula of oxide CaCOCaCO33 ---> CaO + CO ---> CaO + CO22

Review - Complex Eq’nsReview - Complex Eq’ns

Complex = Trans. Metal + LigandComplex = Trans. Metal + Ligand Common Common complexing agentscomplexing agents (aka, ligands) (aka, ligands)

• NHNH33, OH, OH--, SCN, SCN--, CN, CN--

Coordination number = # of ligandsCoordination number = # of ligands• Twice the valence of the Trans MetalTwice the valence of the Trans Metal

Be sure to carefully determine the correct charge Be sure to carefully determine the correct charge on the complexon the complex

Review - Precipitate Eq’nsReview - Precipitate Eq’ns

Common Common precipitating agentsprecipitating agents• Sulfide (SSulfide (S-2-2))• Hydroxide (OHHydroxide (OH--))• Carbonate (COCarbonate (CO33

-2-2))• Phosphate (POPhosphate (PO44

-3-3))• Silver, lead, mercurySilver, lead, mercury• Sulfate (SOSulfate (SO44

-2-2) with Ca, Ba, Sr) with Ca, Ba, Sr Know formulas and valences coldKnow formulas and valences cold Criss-cross valences to get correct formula of PPTCriss-cross valences to get correct formula of PPT

Review - Acid Base Eq’nsReview - Acid Base Eq’ns

Look for obvious acid or base (don’t forget NHLook for obvious acid or base (don’t forget NH33)) Look at other reactant - is it a base or acid?Look at other reactant - is it a base or acid? Proton transferProton transfer Look forLook for

• Conjugates of weak acidsConjugates of weak acids Fluoride, acetate, phosphate, Fluoride, acetate, phosphate,

• Conjugates of weak basesConjugates of weak bases AmmoniumAmmonium

• Oxides, which are anhydridesOxides, which are anhydrides Metal oxides are bases, nonmetal oxides are acidsMetal oxides are bases, nonmetal oxides are acids

• Carbonates, which do the fizzy reaction with acidsCarbonates, which do the fizzy reaction with acids

Review - Redox Eq’nsReview - Redox Eq’ns

Memorize Redox “nuggets”Memorize Redox “nuggets”• Permanganate, chromate, dichromate, nitric acidPermanganate, chromate, dichromate, nitric acid• Also, sulfuric acid, halogen/halide, metal/metal ion, Also, sulfuric acid, halogen/halide, metal/metal ion,

two metal ionstwo metal ions Determine if the nugget is OX or REDDetermine if the nugget is OX or RED Determine if other reactant can be RED or OXDetermine if other reactant can be RED or OX Add half-reactions and balanceAdd half-reactions and balance

The Eq’n Writing ProcessThe Eq’n Writing Process

Scan the list of eight, and as you doScan the list of eight, and as you do• Cross out likely spectatorsCross out likely spectators

But But ONLYONLY if in solution if in solution Sodium, potassium, nitrate are spectatorsSodium, potassium, nitrate are spectators Sulfate can be a spectator, but look out for a PPTSulfate can be a spectator, but look out for a PPT

• Circle key words like Circle key words like solid, liquid, gas, suspension, powder, solid, liquid, gas, suspension, powder, piece of ….piece of ….

These indicate These indicate no spectatorsno spectators

• Underline red flagsUnderline red flags For Redox, AcidBase, PPT, ComplexFor Redox, AcidBase, PPT, Complex

• Label rxn as AB, Comp, PPT, Redox, etc…Label rxn as AB, Comp, PPT, Redox, etc…

Red FlagsRed Flags

Complex formationComplex formation• Ammonia, hydroxide, thiocyanate, cyanideAmmonia, hydroxide, thiocyanate, cyanide

• Other reactant must contain a trans. MetalOther reactant must contain a trans. Metal PPTPPT

• Sulfide, hydroxide, carbonate, phosphate, Ag/Pb/HgSulfide, hydroxide, carbonate, phosphate, Ag/Pb/Hg

• Sulfate with barium/calciumSulfate with barium/calcium Acid BaseAcid Base

• Acid, hydroxide, ammonia, oxide in water, carbonateAcid, hydroxide, ammonia, oxide in water, carbonate RedoxRedox

• Permanganate, chromate, dichromate, nitric acid, peroxidePermanganate, chromate, dichromate, nitric acid, peroxide