Chem : Oct. 1 - Oct. 7. E3 Redox: Transferring Electrons. E3: Redox: Transferring Electrons

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1 hem. 5-6: ct. - ct. 7 Preparation Pre-lab Report (p.90) for E3 completed Discussion Presentation for E completed Pre-lab reading and studies for E3 completed enda ne hour discussion of E(Questions, p.73) Two hours of E3; E3= two session 5 hour lab E3: Redox: Transferring Electrons Session : Two our Lab enda* omplete Part omplete Part A omplete Team Report (Parts and A) * See Student formation Sheet on tools under Resources Experiments. Session : Three our Lab enda omplete Parts and 3 E3 Redox: Transferring Electrons Redox = oxidation-reduction Redox reactions involve electron transfer. Loss of electrons (LE) = oxidation Gain of electrons (GER) = reduction A e s IIA IIIA IVA VA VIA VIIA s e s s s p s p s p 3 s p s p 5 s p 6 a 3s 9 K s 37 Rb 5s 55 s 6s 87 r 7s Mg 3 Si 5 P 6 S 7 l 8 Ar 3s III IV V VI VIIVIII VIII I II 3s 3p 3s 3p 3s 3p 3 3s 3p 3s 3p 5 3s 3p a Sc Ti V r Mn e o i u Zn Ga Ge As Se r Kr s 3d s 3d s 3d 3 s 3d 5 s 3d 5 s 3d 6 s 3d 7 s 3d 8 s s p s p s p 3 s p s p 5 s p 6 3d 0 s 3d 0 s 38 Sr 5s 56 a 6s 88 Ra 7s Y Zr b Mo Tc Ru Rh Pd d 5s d 5s d 3 5s d 5 5s d 5 5s d 7 5s d 8 5s d 0 57 La* 5d 6s ackground formation: Redox Metals lose electrons (LE) on-metals gain electrons GER) 7 d 0 5s 8 d d 0 5s Te 53 I 5 Xe 5s 5p 5s 5p 5s 5p 3 5s 5p 5s 5p 5 5s 5p 6 7 f 73 Ta 7 W 75 Re 76 s g i Rn 5d 6s 5d 3 6s 5d 6s 5d 5 6s 5d 6 6s 5d 7 6s 5d 9 6s 6s 6p 6s 6p 6s 6p 3 6s 6p 6s 6p 5 6s 6p 6 5d 0 6s 5d 0 6s Element synthesized, Ac # but no official name assigned 6d 7s 6d 7s 6d 3 7s 6d 7s 6d 5 7s 6d 6 7s 6d 7 7s Q. Max positive oxidation state of family A metal ions? A s IIA 3 s s Q. xidation states of? VIIA IIIA IVA VA VIA 3 3s 3s VIII III IV V VI VII VIII I II 3s 3p K a Sc Ti V r Mn e o i u Zn Ga Ge s s s 3d s 3d s 3d 3 s 3d 5 s 3d 5 s 3d 6 s 3d 7 s 3d 8 s 3d 0 s 3d 0 s p s p Rb Sr Y Zr b Mo Tc Ru Rh Pd d 5s 5s 5s d 5s d 5s d 3 5s d 5 5s 3d 5 5s d 7 5s d 8 d 0 5s d 0 5s d 0 5s 5p 5s 5p 5s 5p s a La* f Ta W Re s g i 6s 6s 6s 5d 6s 5d 6s 5d 3 6s 5d 6s d 5 6s 5d 6 5d 7 6s 6s 5d 9 6s 5d 0 6s 5d 0 6s 6p 6s 6p 6s 6p 3 6s 6p Element synthesized, r Ra Ac # 7s 7s 7s 6d 7s 6d 7s 7d 3 7s 6d 7s 3d 5 6s 6d 6 6d 7 7s but no official name assigned = 0 or or 8

2 Transition Metals Q. Maximum oxidation state vs. family #? A s IIA 3 8 Redox Reactions IIIA IVA VA VIA VIIA s s s 3s III IV V VI VII VIII VIII I K a Sc Ti 5 3 V 6 r Mn e 9 7 o 0 8 i Zr b Mo Tc Ru Rh Pd 3 0 s 3d0 u Zn 0 LE II 3s 3p 30 a 3 9 s s s 3d s 3d s 3d3 s 3d5 s 3d5 s 3d6 s 3d7 s 3d8 s 3d Rb Sr Y Example of Metal and on-metal Reaction: l al energy 8 d 0 Ga 3 s p s p s 5s 5s d5s d 5s d3 5s d5 5s 3d5 5s d7 5s d8 d0 5s d 5s d 5s 5p 5s 5p 5s 5p s a La* f Ta W Re s g i 0 0 6s 6s 6s 5d 6s 5d 6s 5d3 6s 5d 6s d5 6s 5d6 5d7 6s 6s 5d9 6s 5d 6s 5d 6s 6p 6s 6p 6s 6p3 6s 6p Element synthesized, r Ra Ac# GER Ge DEM but no official name assigned 7s 7s 7s 6d 7s 6d 7s 7d3 7s 6d 7s 3d5 6s 6d6 6d7 7s Redox Reactions Reactants transfer electrons. Reactants change charge (oxidation state). a(s) l (g) al(s) REDX alf Reactions xidation ( > in oxidation state) Reduction ( < in oxidation state) (a a e- ) (l e- l-) alf rxns always written to show electron GAI. The equation = the sum of the half reactions where electrons lost = electrons gained: Lose of e s = oxidation (a a in al) Gain of e s = reduction (l l - in al) XIDIZIG AGET REDUIG AGET Gains electrons and is reduced (GER) Loses electrons and is oxidized (LE) a l a l- Q. Label the reducing agent (RA) and oxidizing agent (A) in the reaction: a l a l- energy RA A A RA The stronger RA and A = reactants; reactants exchange electrons spontaneously and energy is released xidizing agents cause the oxidation of other substances. Reducing agents cause the reduction of other substance. The weaker RA and A products do not exchange electrons

3 Q. ased on the reaction below between a and l, compare sodium metal and chloride ion as reducing agents (RA) a l a l - energy RA A A RA a) l - > a b) a > l - c) l > a d) a > l - Q. ased on the reaction below between a and l, rank the oxidizing agents (A) a l a l - energy RA A A RA Answer: l > a ote that the metal a = RA but its metal ion a = A A e s IIA IIIA IVA VA VIA VIIA s e s s s p s p s p 3 s p s p 5 s p 6 a 3s 9 K s 37 Rb 5s 55 s 6s 87 r 7s Metal ions IA and IIA = oxidizing agents (GER) ther Metal ions = oxidizing or reducing agents Metals = reducing agents (LE) Mg 3 Si 5 P 6 S 7 l 8 Ar 3s III IV V VI VIIVIII VIII I II 3s 3p 3s 3p 3s 3p 3 3s 3p 3s 3p 5 3s 3p a Sc Ti V r Mn e o i u Zn Ga Ge As Se r Kr s 3d s 3d s 3d 3 s 3d 5 s 3d 5 s 3d 6 s 3d 7 s 3d 8 s s p s p s p 3 s p s p 5 s p 6 3d 0 s 3d 0 s 38 Sr 5s 56 a 6s 88 Ra 7s Y Zr b Mo Tc Ru Rh Pd d 5s d 5s d 3 5s d 5 5s d 5 5s d 7 5s d 8 5s d 0 57 La* 5d 6s 7 d 0 5s 8 d d 0 5s Te 53 I 5 Xe 5s 5p 5s 5p 5s 5p 3 5s 5p 5s 5p 5 5s 5p 6 7 f 73 Ta 7 W 75 Re 76 s g i Rn 5d 6s 5d 3 6s 5d 6s 5d 5 6s 5d 6 6s 5d 7 6s 5d 9 6s 6s 6p 6s 6p 6s 6p 3 6s 6p 6s 6p 5 6s 6p 6 5d 0 6s 5d 0 6s Element synthesized, Ac # but no official name assigned 6d 7s 6d 7s 6d 3 7s 6d 7s 6d 5 7s 6d 6 7s 6d 7 7s Multiple oxidation state metal ions Some metal ions can act as an oxidizing or reducing agent! Example: = 0, and ion can gain electrons = A: e- ion can lose electrons = RA: e- Predicting Redox Strength Electronegativity and Redox Strength Electronegativity and Redox Strength Electronegativity values (p., manual) reflect an elements attraction for electrons when forming a bond Electronegativity of the elements IA IIA III IV V VI VII VIII I II IIIA IVA VA VIA VIIA Si P S l K a Sc Ti V r Mn e o i u Zn Ga Ge As Se r Rb Sr Y Zr b Mo Tc Ru Rh Pd d Te I s a La f Ta W Re s Lu.3.7 r Ra Ac Th Pa U p- o g i = Metalloids = onmetals = Metals

4 IA IIA III IV V VI VII VIII I II IIIA IVA VA VIA VIIA..0 Q. Where are the best oxidizing agents located in the electronegativity table? 0.9. K a Sc Ti V r Mn e o Rb Sr Y Zr b Mo Tc Ru Rh s a La f Ta W Re s Lu.3.7 r Ra Ac Th Pa U p- o Si P S l. i u Zn Ga Ge As Se r Pd d Te I.7.7. g i. ote: The element is in the area (upper right corner) IA IIA III IV V VI VII VIII I II IIIA IVA VA VIA VIIA..0 Q. Where are the best reducing agents located in the electronegativity table? 0.9. K a Sc Ti V r Mn e o Rb Sr Y Zr b Mo Tc Ru Rh s a La f Ta W Re s Lu.3.7 r Ra Ac Th Pa U p- o Si P S l. i u Zn Ga Ge As Se r Pd d Te I.7.7. g i. ote: The element Ra is in the area (lower left hand corner) Part IA. Metal reactions with water Rank the reducing agent strength of the metals a, K, Mg, and a from experimental observations. orrelate reactivity results with the position of the metal in the periodic table. IA IIA III IV V VI VII VIII I II IIIA IVA VA VIA VIIA..0 Q. Predict the RA strength of Mg and a based on position and electronegativity values K a Sc Ti V r Mn e o Rb Sr Y Zr b Mo Tc Ru Rh s a La f Ta W Re s Lu.3.7 r Ra Ac Th Pa U p- o > a Mg Si P S l. i u Zn Ga Ge As Se r Pd d Te I.7.7. g i. Experimental omparison of a and Mg Experimental omparison of a and Mg Metal Water metal hydroxide (g) RA A A RA Example: Mg(s) (l) Mg()(s) (g) DEM RA: a > Mg

5 Q. Predict the RA strength of K and a compared to Mg and a based on electronegativity values. IA IIA..0 a 0.9 K 0.8 Rb 0.8 s 0.7 r 0.7 Mg. a.0 Sr.0 a 0.9 Ra 0.9 III IV V Sc.3 Y. La -Lu Ac. Ti Zr. f.3 Th.3 V.6 b.6 Ta Pa VIII VI VII r.6 Mo W.7 U.7 Mn Tc Re p- e Ru s o.3 o Rh I i Pd u. II IIIA IVA VA VIA VIIA Zn.6 d.7 g Ga.6.7 Si Ge P. As i Reactivity of K and a Experimental determination of the reactivity of K and a compared to a and Mg S Se. Te. l r.8 I DEM K a > a > >Mg Experimental omparison of K, a, a, and Mg Part I. Predicting Metal Reactivity. Experimentally determine the reducing agent (RA) strength of four team assigned metals a skitters around the water surface K skitters around the water surface and ignites RA: K > a > a > Mg formation: nly three of the four metals will be provided our of the assigned metal s ions will be provided Prediction from electronegativity values and experimental results agree Part Experiment Design Example You need to determine the reducing agent strength of, u, and. Table Design for Part. reate a table for recording data (pre-lab). u formation: Solutions of metal ions, u, in the form of 0.0 M metal ion nitrate salts u and only (i.e., is unavailable) u Reducing agents (metals) on one side and oxidizing agents (metal ions) on other side.

6 Part experiment Metal and Metal ion reactions ombine different available metals and metal ions (0.0 M metal ion nitrates) u u u(s) 3(aq)? (s) u(3)(aq)? DEM Q. ased on experiment results, rank: -The oxidizing agents ( and u) - The reducing agents ( and u) A: > u u(s) (aq) YES A: > u Stronger RA and A = Reactants Enter results into Part Table Test remaining available metal - metal ion combinations u u(s) (aq) (s) u(aq) (s) u(aq) Part experiment Metal and Metal Ion Reactions RA: u > RA: u > u YES

7 Metal and Metal ion reactions Part experiment Enter results into Part Table u u YES u(s) ( 3 ) (aq)? (s) ( 3 ) (aq)? DEM Q. omplete the table below and indicate the comparative RA strength of, u, and. u u YES YES YES 0 RA strength: > u > Questions? ontact nkerner@umich.edu