REACTIONS IN Predicting whether a reaction will occur Reactions with a solid product Describing reactions in aqueous solutions Reactions that form water: Acids and Bases Reactions of metals with nonmetals (OxidationReduction Reactions) Classification of reactions Other classifications Homework Problems: 7.1: 2 7.2: 3, 4, 9, 10, 11, 13, 21, 22 7.3: 25, 26 7.4: 39 7.5: 50 7.6: 54 7.7: 61, 64, 66
REACTIONS IN Predicting whether a reaction will occur JUST BECAUSE A REACTION IS POSSIBLE DOES NOT NECESSARILY MEAN IT WILL OCCUR. THERE ARE TWO ISSUES: 1. WHETHER A REACTION WANTS TO OCCUR Paper + oxygen Reactants carbon dioxide + water Products 2. WHETHER SUFFICIENT ENERGY IS PRESENT TO START THE PROCESS SOME POTENTIAL DRIVING FORCES *Formation of a solid *Formation of (removable) water *Transfer of electrons *Formation of a gas
REACTIONS IN Reaction is which a solid forms One driving force is formation of a solid: PRECIPITATION KCl (aq) + AgNO 3 (aq) Colorless Colorless Precipitate CHEMICAL CHANGE OCCURRED. WHAT CHEMICAL REACTION FORMULA DESCRIBES WHAT HAPPENED Break the problem up: Reactant entities known. What happens when these dissolve in water? What possible products could form? Can we guess what the precipitate might be? Are there rules to guide us on what precipitates?
REACTIONS IN Reactants dissolving in water KCl (aq) + AgNO 3 (aq) Colorless Colorless The starting solids are ionic compounds. They are neutral. When dissolved in water, they separate and the individual ions move around separately. This can be demonstrated through in creased conductivity of water that they are dissolved in. STRONG ELECTROLYTE: Substance which when dissolved in water increases conductance of water.
ADDITIONAL EXAMPLES IN Reactants dissolving in water KCl (aq) + AgNO 3 (aq) Colorless Colorless K + K + K + Cl K + Cl Cl Cl Ag + NO 3 NO 3 Ag + Ions separate. Ratios of ions determined by original compound K + (aq)+ Cl (aq)+ag + (aq)+no 3 (aq)
REACTIONS IN How to decide what products form KCl (aq) + AgNO 3 (aq) Colorless Colorless K + (aq)+ Cl (aq)+ag + (aq)+no 3 (aq) K + NO 3 KNO 3 Cl KCl Ag + Ag NO 3 AgCl Like charged ions don t combine Likely Starting solutions do not precipitate precipitate Products have net charge of zero Think of possible verification experiments
REACTIONS IN Final Description KCl (aq) + AgNO 3 (aq) Colorless Colorless AgCl (s) + KNO 3 (aq) White Colorless NO 3 AgCl AgCl K + K+ NO 3
REACTIONS IN Reaction is which a solid forms One driving force is formation of a solid: PRECIPITATION K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless Yellow Precipitate CHEMICAL CHANGE OCCURRED. WHAT CHEMICAL REACTION FORMULA DESCRIBES WHAT HAPPENED Break the problem up: Reactant entities known. What happens when these dissolve in water? What possible products could form? Can we guess what the precipitate might be? Are there rules to guide us on what precipitates?
REACTIONS IN Reactants dissolving in water The starting solids are ionic compounds. They are neutral. K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless When dissolved in water, they separate and the individual ions move around separately. This can be demonstrated through in creased conductivity of water that they are dissolved in. STRONG ELECTROLYTE: Substance which when dissolved in water increases conductance of water.
ADDITIONAL EXAMPLES IN Reactants dissolving in water K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless K + CrO 2 4 K + K + CrO 2 4 K + Ba 2+ NO 3 NO 3 NO 3 Ba 2+ NO 3 Ions separate. Ratios of ions determined by original compound 2K + (aq)+ CrO 4 2 (aq)+ba 2+ (aq)+2no 3 (aq)
REACTIONS IN How to decide what products form K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless 2K + (aq)+ CrO 4 2 (aq)+ba 2+ (aq)+2no 3 (aq) NO 3 CrO 4 2 K + KNO 3 K 2 CrO 4 Ba 2+ BaNO 3 BaCrO 4 Like charged ions don t combine Likely Starting solutions do not precipitate precipitate Products have net charge of zero Think of possible verification experiments
REACTIONS IN Final Description K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless BaCrO 4 (s) + 2KNO 3 (aq) Yellow Colorless NO 3 K + K+ NO 3 BaCrO 4
DESCRIBING REACTIONS IN Observation: Molecular Equation: K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) BaCrO 4 (s) + 2KNO 3 (aq) Complete Ionic Equation: 2K + (aq)+ CrO 4 2 (aq)+ba 2+ (aq)+2no 3 (aq) BaCrO 4 (s) + 2K + (aq)+ 2NO 3 (aq) Net Ionic Equation: K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq) Yellow Colorless Yellow Precipitate SPECTATOR IONS Ba 2+ (aq) + CrO 4 2 (aq) BaCrO 4 (s)
ADDITIONAL EXAMPLES IN Reactants dissolving in water Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) Na + Na + Na + Na + SO 4 2 SO 4 2 Pb 2+ NO 3 NO 3 NO 3 Pb 2+ NO 3 Ions separate. Ratios of ions determined by original compound 2Na + (aq)+ SO 4 2 (aq)+pb 2+ (aq)+2no 3 (aq)
REACTIONS IN How to decide what products form Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) 2Na + (aq)+ SO 4 2 (aq)+pb 2+ (aq)+2no 3 (aq) NO 3 SO 4 2 Na + NaNO 3 Na 2 SO 4 Pb 2+ PbNO 3 PbSO 4 Like charged ions don t combine Likely Starting solutions do not precipitate precipitate Products have net charge of zero Think of possible verification experiments
REACTIONS IN Final Description Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) PbSO 4 (s) + Precipitate 2NaNO 3 (aq) Colorless NO 3 Na + Na+ NO 3 PbSO 4
DESCRIBING REACTIONS IN Observation: Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) Molecular Equation: Na 2 SO 4 (aq) + Pb(NO 3 ) 2 (aq) PbSO 4 (s) + 2NaNO 3 (aq) Complete Ionic Equation: 2Na + (aq)+ SO 4 2 (aq)+pb 2+ (aq)+2no 3 (aq) PbSO 4 (s) + 2Na + (aq)+ 2NO 3 (aq) Net Ionic Equation: Precipitate SPECTATOR IONS Pb 2+ (aq) + SO 4 2 (aq) PbSO 4 (s)
REACTIONS THAT FORM WATER: ACIDS AND BASES TWO VERY IMPORTANT CLASSES OF COMPOUNDS. Mineral acids known as far back as the 1300 In late 1800s, Arrhenius proposed that. An acid is a substance that produces H + ions (protons) when it is dissolved in water. Strong acids dissociate completely into protons and the counter anion (Stong electrolytes). HCl (g) HNO 3 H 2 SO 4 H + (aq) + Cl (aq) H + (aq)+ NO 3 (aq) H + (aq)+ HSO 4 (aq)
REACTIONS THAT FORM WATER: ACIDS AND BASES TWO VERY IMPORTANT CLASSES OF COMPOUNDS. A Base is a substance that produces OH ions (hydroxide ions) when it is dissolved in water. Strong bases dissociate completely into hydroxide ions and the counter cation. NaOH (s) KOH (s) Na + (aq) + OH (aq) K + (aq)+ OH (aq)
ACIDS and BASES Dissolved in water HCl (aq) + NaOH (aq) Cl Na Cl + Na + OH H + H + OH OH Cl Na H + + Cl OH Na + H + Ions separate. Ratios of ions determined by original compound
ACIDBASE REACTIONS IN HCl (aq) + NaOH (aq) Colorless Colorless H + (aq)+ OH (aq)+na + (aq)+cl (aq) H + OH H 2 O Cl HCl Na + NaOH NaCl Like charged ions don t combine Starting solutions do not precipitate Products have net charge of zero
DESCRIBING REACTIONS BETWEEN ACIDS AND BASES Observation: HCl (aq) + NaOH (aq) Colorless Colorless Molecular Equation: Colorless HCl(aq) + NaOH(aq) NaCl(aq) + H 2 O (l) Complete Ionic Equation: H + (aq) + Cl (aq) + Na + (aq) + OH (aq) H 2 O (l) + Na + (aq) + Cl (aq) Net Ionic Equation: SPECTATOR IONS H + (aq) + OH (aq) H 2 O (l) Note salt formation!
DESCRIBING REACTIONS BETWEEN ACIDS AND BASES Observation: HNO 3 (aq) + KOH (aq) Colorless Colorless Molecular Equation: Colorless HNO 3 (aq) + KOH(aq) KNO 3 (aq) + H 2 O (l) Complete Ionic Equation: H + (aq) + NO 3 (aq) + K + (aq) + OH (aq) H 2 O (l) + K + (aq) + NO 3 (aq) Net Ionic Equation: SPECTATOR IONS H + (aq) + OH (aq) H 2 O (l) Note salt formation!
REACTIONS OF METALS WITH NONMETALS (OXIDATIONREDUCTION REACTIONS): TO LEARN GENERAL CHARACTERISTICS OF A REACTION BETWEEN A METAL AND A NONMETAL TO RECOGNIZE ELECTRON TRANSFER AS A DRIVING FORCE FOR A CHEMICAL REACTION IONIZATION OF SODIUM Na Na + + e IONIZATION OF FLUORINE F + e F 23 Na 11 23 Na + 11 19 F 9 19 F 9 11 + 11 + 9 + 9 + 11 10 9 10 Neutral Sodium Atom Sodium Ion Fluorine Atom Fluoride Ion
AN OXIDATIONREDUCTION REACTION e 11 + 11 Sodium Atom 9 + 9 Fluorine Atom 11 + 10 Sodium Ion (+) + 9 + 10 Fluorine Ion () 2Na + F 2 2 NaF
Examples of OxidationReduction Reactions 2Mg(s) + O 2 (g) 2MgO(s) Mg Mg 2+ + 2e O + 2e O 2 Mg 2e O Mg 2+ O 2 Mg 2e O Mg 2+ O 2
Examples of OxidationReduction Reactions 2Al(s) + Fe 2 O 3 (s) 2Fe(s) + Al 2 O 3 (s) Al Al 3+ + 3e Fe 3+ + 3e Fe 3e Fe Al Fe 3+ Al 3+ O O O O O O Al Fe 3+ Al 3+ 3e Fe
Examples of OxidationReduction Reactions 2Al(s) + 3I 2 (s) 2Al I 3 (s) Al Al 3+ + 3e I + e I I I I Al 3+ I Al I Al I I Al 3+ I I I I I
CLASSIFICATION SCHEMES FOR REACTIONS: FORMATION OF A SOLID FORMATION OF WATER TRANSFER OF ELECTRONS One Approach K 2 CrO 4 + Ba(NO 3 ) 2 BaCrO 4 + 2KNO 3 Solution Solution Solid Solution Precipitation Reaction Double displacement Reaction HCl + NaOH NaCl + H 2 O Solution Solution Solution Liquid AcidBase Reaction 2Na + F 2 FORMATION OF A GAS 2 NaF Solid Gas Solid OxidationReduction Reaction 2HCl + Na 2 CO 3 CO 2 + H 2 O + NaCl Solution Solution Gas Liquid Solution
CLASSIFICATION SCHEMES FOR REACTIONS: COMBUSTION REACTIONS Another Approach C 3 H 8 + 5 O 2 3 CO 2 + 4H 2 O Propane Gas Gas Gas Gas C 8 H 18 + 25 O 2 16 CO 2 + 18 H 2 O Gasoline liquid Gas Gas Gas C + O 2 CO 2 Coal solid Gas Gas SYNTHESIS (COMBINATION) REACTIONS 2H 2 + O 2 H 2 O C + O 2 CO 2 N 2 + O 2 2NO DECOMPOSITION REACTIONS 2H 2 O 2H 2 + O 2 2HgO 2Hg + O 2 2NaCl 2Na + Cl 2