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Regent’s Warm-Up

Regent’s Warm-Up. What is the electron configuration of a sulfur atom in the ground state? (1) 2 – 4 (3) 2 – 8 – 4 (2) 2 – 6 (4) 2 – 8 – 6. Regent’s Warm-Up. What is the electron configuration of a sulfur atom in the ground state? (1) 2 – 4 (3) 2 – 8 – 4

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Regent’s Warm-Up

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  1. Regent’s Warm-Up What is the electron configuration of a sulfur atom in the ground state? (1) 2–4 (3) 2–8–4 (2) 2–6 (4) 2–8–6

  2. Regent’s Warm-Up What is the electron configuration of a sulfur atom in the ground state? (1) 2–4 (3) 2–8–4 (2) 2–6 (4) 2–8–6

  3. s AIM: What are Oxidation-Reduction Reactions? Do Now: If the conc. Of a product is increased how will the equilibrium state be affected? Oxidation Reduction Reactions

  4. Purifying metals (e.g. Al, Na, Li) Producing gases (e.g. Cl2, O2, H2) Electroplating metals Electrical production (batteries, fuel cells) Protecting metals from corrosion Balancing complex chemical equations Sensors and machines (e.g. pH meter) Oxidation Reduction Reactions What are they used for? Why are they important?…

  5. Oxidation Reduction Reactions Classical Definitions • Oxidation – the combination of a substance with oxygen Example: 2Mg(s) + O2(g) 2MgO(s) • O2 is the OXIDIZING AGENT • Mg gains oxygen and is oxidized

  6. Oxidation Reduction Reactions Classical Definitions • Reduction – the removal of O2 from a substance Example: CuO(aq) + H2(g) Cu(s) + H2O(l) • H2 is the REDUCING AGENT • CuO loses oxygen and is reduced

  7. Oxidation Reduction Reactions Current Definitions Take into account the charge of the ions and atoms involved in the reaction • Oxidation – the Loss of Electrons Example: 2Mg0 + O20 2Mg+2O-2 • The oxidation # of Mg goes from 0 to +2 • Since Mg0lost 2e-s, Mg0 is OXIDIZED 2Mg0 2Mg+2 + 4e-

  8. Oxidation Reduction Reactions Current Definitions • Reduction – the Gain of Electrons Example: Cu+2O-2 + H20 Cu0 + H2+1O-2 • If you look closely oxygen is not reacting, its oxidation # stays the same (-2) • Copper goes from Cu+2 to Cu0 • Copper gains 2e-s & is REDUCED Cu+2 + 2e-s  Cu0

  9. What is the MAIN difference between the classical and current definitions? *Oxygen is NOT required in the current definition* Which particles are gained and lost during a redox reaction? (1) electrons (2) protons (3) neutrons (4) positrons Oxidation Reduction Reactions

  10. Oxidation and Reduction reactions are opposite processes that occur simultaneously For something to lose an electron there must be something else that wants to gain that electron In a redox reaction, how does the total number of electrons lost by the oxidized substance compare to the total number of electrons gained by the reduced substance? 1. The number lost is always greater than the number gained. 2. The number lost is sometimes equal to the number gained. 3. The number lost is always equal to the number gained. 4. The number lost is sometimes less than the number gained. Oxidation Reduction Reactions

  11. Loss of Electrons is Oxidation Gain of Electrons is Reduction LEO the lion says GER Oxidation Reduction Reactions

  12. The substance that loses electrons is OXIDIZED and is the REDUCING AGENT The substance that gains electrons is REDUCED and is the OXIDIZING AGENT In any redox reaction, the substance that undergoes reduction will 1. lose electrons and have a decrease in oxidation number 2. gain electrons and have a decrease in oxidation number 3. lose electrons and have an increase in oxidation number 4. gain electrons and have an increase in oxidation number Oxidation Reduction Reactions

  13. Which half-reaction correctly represents reduction? 1. Ag --> Ag+ + e- 2. Au3+ + 3e- --> Au 3. F2 --> 2 F- + 2e- 4. Fe2+ + e- --> Fe3+ Given the balanced ionic equation representing a reaction: 2Al3+(aq) + 3Mg(s) → 3Mg2+(aq)+2Al(s) In this reaction, electrons are transferred from 1. Al to Mg2+3. Mg to Al3+ 2. Al3+ to Mg 4. Mg2+ to Al Oxidation Reduction Reactions 3Mg2+(aq)+2Al(s)

  14. Given the balanced equation representing a redox reaction:2Al + 3Cu2+ --> 2Al3+ + 3Cu Which statement is true about this reaction? 1. Each Al loses 2e- and each Cu2+ gains 3e-. 2. Each Al3+ gains 2e- and each Cu loses 3e-. 3. Each Al loses 3e- and each Cu2+ gains 2e-. 4. Each Al3+ gains 3e- and each Cu loses 2e-. In any redox reaction, a reactant can undergo a decrease in oxidation number by 1. losing electrons, only 2. losing protons, only 3. gaining electrons, only 4. gaining protons, only Oxidation Reduction Reactions

  15. Given the reaction shown:Which species undergoes oxidation? 1. Mg(s) 2. Cl-(aq) 3. H+(aq) 4. H2(g) Which changes occur when Pt2+ is reduced? 1. The Pt2+ gains electrons and its oxidation number increases. 2. The Pt2+ loses electrons and its oxidation number increases. 3. The Pt2+ gains electrons and its oxidation number decreases. 4. The Pt2+ loses electrons and its oxidation number decreases Oxidation Reduction Reactions

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