Chapter 17 Oxidation and Reduction Redox Oxidation Numbers Balancing by Redox Quiz Corrections Electrolysis Lab A-Electrolysis Electrolysis Lab Results Concept Check Assignment Quiz-Balancing/Electrolysis Lab C Faradays Lab Electrolysis Quiz Correction Lab B Voltaic Cell Pages Notes One Unit Twelve Redox Oxidation Numbers Balancing by Redox Redox Burning: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O+ Heat Rusting Iron: 4Fe + 3O 2 2Fe 2 O 3 + Heat Oxidation - Loss of e -1. Na(s) Na +1 +1e -1 Reduction - Gain of e -1. Cl 2 + 2e -1 2Cl -1 Number line (OxidationLeft or right?) Demonstration combustible blown through a burner. Key Elements (99%) H +1 H -1 (99%)O -2 O -1 (Always) Li +1, Na +1, K +1, Rb +1, Cs +1, Fr +1 (Always) Be +2, Mg +2, Ca +2, Ba +2, Sr +2, Ra +2 (Always) Al +3 (with only a metal) F -1, Cl -1, Br -1, I -1 (NO 3 -1 ) ion is always +5 (SO 4 -2 ) ion is always +6 Finding Oxidation Numbers +1-2 H2OH2O 2(+1)+1(-2)=Zero The sum of the oxidation numbers must be equal to _____ for a compound. Find Ox#s for H 2 O? zero 2(H)+1(O)=Zero H 3 PO 4 Find Ox#s for H 3 PO 4 ? 3(H)+4(O)=Zero +5 1(P)+ 3(+1)+4(-2)=Zero1(+5)+ Finding Oxidation #s for Compounds H 3 PO 4 H2OH2O HNO H 2 SO Hg 2 SO Na 2 Cr 2 O H 2 CO (NH 4 ) 2 CO Ca 3 (AsO 4 ) Fe 2 (SO 4 ) Ba(ClO 4 ) Al 2 (CO 3 ) Balancing By Redox Example One H 2 O + P 4 + H 2 SO 4 H 3 PO 4 + H 2 S #1. Find the oxidation #s. #2. ID the element (i) oxidized and (ii) reduced. #3. Find # of electrons lost or gained. #4. Cross-multiply. #5. Balance using whole # ratios. #6. Find whole number coefficients e -1 lost 8e -1 Gained X8 X Multiply by 1. 12H 2 O +2P 4 +5H 2 SO 4 8H 3 PO 4 +5H 2 S Balancing By Redox Example Two K 3 PO 4 + Cl 2 P 4 + K 2 O+ KClO 2 #1. Find the oxidation #s. #2. ID the element (i) oxidized and (ii) reduced. #3. Find # of electrons lost or gained. #4. Cross-multiply. #5. Balance using whole # ratios. #6. Find whole number coefficients e -1 Gained 3e -1 Lost X3 X5 5/223/453 Multiply by 4. 12K 3 PO 4 +10Cl 2 3P 4 +8K 2 O+20KClO 2 Notes Two Unit Twelve Quiz Corrections Electrolysis Lab A-Electrolysis NO H + +e - NO 2 (g)+H 2 O Fe 3+ +e - Fe 2+ I 2 (s)+2e - 2I - Cu + +e - Cu(s) Cu 2+ +2e - Cu(s) SO H + +2e - SO 2 (g) Sn 4+ +2e - Sn(s) 2H + +2e - H 2 (g) Pb 2+ +2e - Pb(s) Sn 2+ +2e - Sn(s) Ni 2+ +2e - Ni(s) Co 2+ +2e - Co(s) 2H + (pH=7)+2e - H 2 (g) Fe 2+ +2e - Fe(s) Cr 3+ +3e - Cr(s) Zn 2+ +2e - Zn(s) 2H 2 O+2e - 2OH - +H 2 (g) Hg 2+ +2e - Hg(l) Ag + +e - Ag(l) /2O 2 (g)+2H + (pH=7)+2e - H 2 O NO H + +3e - NO(g)+2H 2 O Br 2 (l)+2e - 2Br /2O 2 (g)+2H + (pH=7)+2e - H 2 O Reducing Agent Stronger Reducing Agent Loses e - Oxidizing Agent Weaker Oxidizing Agent Gains e - StrongerWeaker Electrolysis anode Cathode e -1 Electrolysis Cathode Anode Electron flow? Mass Gain=? Which is the Cathode=? Anode=? Cathode(spoon) Mass Loss=? Copper -reduction -oxidation -electric current produced chemical reaction Electrolysis Lab- Demo KI (aq) What is available to react? K +1 I -1 H2OH2O Anode Reaction lowest reaction on right. Cathode Reaction highest reaction on left. NO H + +e - NO 2 (g)+H 2 O Fe 3+ +e - Fe 2+ I 2 (s)+2e - 2I - Cu + +e - Cu(s) Cu 2+ +2e - Cu(s) SO H + +2e - SO 2 (g) Sn 4+ +2e - Sn(s) 2H + +2e - H 2 (g) Pb 2+ +2e - Pb(s) Sn 2+ +2e - Sn(s) Ni 2+ +2e - Ni(s) Co 2+ +2e - Co(s) 2H + (pH=7)+2e - H 2 (g) Fe 2+ +2e - Fe(s) Cr 3+ +3e - Cr(s) Zn 2+ +2e - Zn(s) 2H 2 O+2e - 2OH - +H 2 (g) Hg 2+ +2e - Hg(l) Ag + +e - Ag(l) /2O 2 (g)+2H + (pH=7)+2e - H 2 O NO H + +3e - NO(g)+2H 2 O Br 2 (l)+2e - 2Br /2O 2 (g)+2H + (pH=7)+2e - H 2 O K +1 I -1 H2OH2O K + +e - K(s) An: lowest on right. Cath: highest on left. 2I - I 2 (s)+2e - We see brown:I 2 (s) We see pink. We saw bubbles KI(aq) NO H + +e - NO 2 (g)+H 2 O Fe 3+ +e - Fe 2+ I 2 (s)+2e - 2I - Cu + +e - Cu(s) Cu 2+ +2e - Cu(s) SO H + +2e - SO 2 (g) Sn 4+ +2e - Sn(s) 2H + +2e - H 2 (g) Pb 2+ +2e - Pb(s) Sn 2+ +2e - Sn(s) Ni 2+ +2e - Ni(s) Co 2+ +2e - Co(s) 2H + (pH=7)+2e - H 2 (g) Fe 2+ +2e - Fe(s) Cr 3+ +3e - Cr(s) Zn 2+ +2e - Zn(s) 2H 2 O+2e - 2OH - +H 2 (g) Hg 2+ +2e - Hg(l) Ag + +e - Ag(l) /2O 2 (g)+2H + (pH=7)+2e - H 2 O NO H + +3e - NO(g)+2H 2 O Br 2 (l)+2e - 2Br /2O 2 (g)+2H + (pH=7)+2e - H 2 O Na + +e - Na(s) An: lowest(right) Cath: highest(left) H 2 O 1/2O 2 (g)+2H + (pH=7)+2e - We saw bubbles! We saw copper on the pencil tip! Cu +2 SO 4 -2 H2OH2O CuSO 4 (aq) NO H + +e - NO 2 (g)+H 2 O Fe 3+ +e - Fe 2+ I 2 (s)+2e - 2I - Cu + +e - Cu(s) Cu 2+ +2e - Cu(s) SO H + +2e - SO 2 (g) Sn 4+ +2e - Sn(s) 2H + +2e - H 2 (g) Pb 2+ +2e - Pb(s) Sn 2+ +2e - Sn(s) Ni 2+ +2e - Ni(s) Co 2+ +2e - Co(s) 2H + (pH=7)+2e - H 2 (g) Fe 2+ +2e - Fe(s) Cr 3+ +3e - Cr(s) Zn 2+ +2e - Zn(s) 2H 2 O+2e - 2OH - +H 2 (g) Hg 2+ +2e - Hg(l) Ag + +e - Ag(l) /2O 2 (g)+2H + (pH=7)+2e - H 2 O NO H + +3e - NO(g)+2H 2 O Br 2 (l)+2e - 2Br /2O 2 (g)+2H + (pH=7)+2e - H 2 O Na + +e - Na(s) An: lowest(right) Cath: highest(left) H 2 O 1/2O 2 (g)+2H + (pH=7)+2e - We saw bubbles. We saw pink. We saw bubbles Na +1 SO 4 -2 H2OH2O Na 2 SO 4 (aq) Electrolysis lab A Notes Three Unit Twelve Electrolysis Lab Results Concept Check Assignment Quiz-Balancing/Electrolysis Notes Four Unit Twelve Faradays Law Lab B This as a chemical process that uses electricity to produce industrial quantities of specific chemicals. Application of Faradays law F = C/mol e - ) A x s = C Faradays Law: Lab B Fe(s) NO 3 -1 e -1 Anode? Cathode? Lose Mass? Gain Mass? Fe +3 3e -1 Fe +3 NO 3 -1 F = C/mole - Amp x second = C Faradays Law Calculation One 3.0 amp x Au +3 +3e -1 Au(s) 60 min 1 hour 1.5 Hour x 60 Sec 1 min =16000C 16000C x 1mole e C = 0.17 mol e mol e -1 x 1 m Au(s) 3mol e -1 =0.056mol Au(s) 0.056mol Au(s)x 197.0gAu 1mol Au = 11g Au 1. Balanced Equation 2. Calculate Coulombs. 3. Calculate moles e Calculate moles of substance. 5. Calculate grams. How many grams of Gold will be plated, using a current of 3.0 amps for 1.5 hours? x Faradays Law Calculation Two 2.0 amp x Ag +1 +1e -1 Ag(s) 45 Hour x 60 Sec 1 min =5400C 5400C x 1mole e C = mol e mol e -1 x 1 m Ag(s) 1mol e -1 =0.056mol Au(s) mol Au(s)x 107.9gAg 1mol Ag = 6.0 g Ag 1. Balanced Equation 2. Calculate Coulombs. 3. Calculate moles e Calculate moles of substance. 5. Calculate grams. How many grams of Silver will be plated, using a current of 2.0 amps for 45 minutes? Salt Bridge Cu +2 SO 4 -2 Cr +3 SO 4 -2 Cr +3 SO 4 -2 Cathode Anode Cu e -1 Cu Cr Cr +3 +3e -1 Overall rxn: 2Cr+ x3 x Cu +2 2Cr Cu emf=1.08volts 1.08 Cr +3 3e -1 SO 4 -2 Na +1 Cu(s)Cr(s) Salt Bridge e -1 ? rxn: Cathode Verses Anode Formation of Rust Fe(OH) 2 (s) Fe +2 H2OH2O e -1 Fe +2 e -1 H2OH2O O2O2 OH -1 Fe(OH) 2 (s) Fe +2 H2OH2O e -1 Fe +2 e -1 H2OH2O O2O2 OH -1 Fe(OH) 2 (s) O2O2 H2OH2O H2OH2O Fe(OH) 3 (s) Ion-Electron Method for Balancing UO I 2 U +4 + IO 3 -1 (Acid) UO 2 +2 I 2 U +4 + H 2 O #2. Bal Non-O Elem. #3. + H 2 O. #4. + H +1. #5. + e -1 to bal +/ H e -1 2 #1. Separate Half-rxn. IO H 2 O 6 + H e X 1X UO 2 +2 I 2 U +4 + H 2 O10 + H e IO H 2 O 6 + H e UO U H 2 O4+ H I 2 1 IO Ion-Electron Method for Balancing IO Ti +3 I 2 + TiO 2 +1 (Acid) IO 3 -1 Ti +3 I 2 + H 2 O #2. Bal Non-O Elem. #3. + H 2 O. #4. + H +1. #5. + e -1 to bal +/ H e #1. Separate Half-rxn. TiO H 2 O 2 + H e X 5X IO 3 -1 Ti +3 I 2 + H 2 O6 + H e TiO H 2 O 10 + H e IO I H H 2 O4 + Ti +3 5 TiO NO H + +e - NO 2 (g)+H 2 O Fe 3+ +e - Fe 2+ I 2 (s)+2e - 2I - Cu + +e - Cu(s) Cu 2+ +2e - Cu(s) SO H + +2e - SO 2 (g) Sn 4+ +2e - Sn(s) 2H + +2e - H 2 (g) Pb 2+ +2e - Pb(s) Sn 2+ +2e - Sn(s) Ni 2+ +2e - Ni(s) Co 2+ +2e - Co(s) 2H + (pH=7)+2e - H 2 (g) Fe 2+ +2e - Fe(s) Cr 3+ +3e - Cr(s) Zn 2+ +2e - Zn(s) 2H 2 O+2e - 2OH - +H 2 (g) Hg 2+ +2e - Hg(l) Ag + +e - Ag(l) /2O 2 (g)+2H + (pH=7)+2e - H 2 O NO H + +3e - NO(g)+2H 2 O Cl 2 (g)+2e - 2Cl /2O 2 (g)+2H + (pH=7)+2e - H 2 O K + +e - K(s) An: lowest(right) Cath: highest(left) H 2 O 1/2O 2 (g)+2H + (pH=7)+2e - We would see bubbles and no pink. We would see solid metal Ni +2 Cl -1 H2OH2O NiCl 2 (aq) Balancing By Redox Example Four Cs 3 AsO 4 + Cl 2 As+ Cs 2 O+ CsClO 2 #1. Find the oxidation #s. #2. ID the element (i) oxidized and (ii) reduced. #3. Find # of electrons lost or gained. #4. Cross-multiply. #5. Balance using whole # ratios. #6. Find whole number coefficients e -1 Gained 3e -1 Lost X3 X5 5/ Multiply by 2. 6Cs 3 AsO 4 + 5Cl 2 6As+4Cs 2 O+10CsClO 2