The Battery Writing Oxidation and Reduction Reactions You will need a partner, a periodic table and the Activity Series on pg. 357.

The Voltaic Cell = A Battery Anode = negative/Oxidation = losing electrons Anode = negative/Oxidation = losing electrons Cathode = positive/Reduction = gaining electrons Cathode = positive/Reduction = gaining electrons Voltage: the unit of a battery Voltage: the unit of a battery The electron in the battery ALWAYS flows from negative to positive The electron in the battery ALWAYS flows from negative to positive

(Negative)(Positive) Zinc Sulfate solution Copper Sulfate solution Zinc Metal Copper Metal

Using the Activity Series on pg. 357 To determine which metal of the battery will be the negative (anode/Oxidation/losing electrons) and which metal of the battery will be the positive (cathode/Reduction/gaining electrons) you need to use the activity series. To determine which metal of the battery will be the negative (anode/Oxidation/losing electrons) and which metal of the battery will be the positive (cathode/Reduction/gaining electrons) you need to use the activity series. The metal on the top of the activity series would be the negative (anode/Oxidation/losing electrons) and the metal on the bottom of the activity series will be the positive (cathode/Reduction/gaining electrons) you need to use the activity series. The metal on the top of the activity series would be the negative (anode/Oxidation/losing electrons) and the metal on the bottom of the activity series will be the positive (cathode/Reduction/gaining electrons) you need to use the activity series.

Positive or Negative? The electron in the battery ALWAYS flows from negative to positive 1. Li ______Mg ______ 2. Fe _____Ba _______ 3. Au _____Hg _______ 4. Sn _____Pb _______ 5. K ______Ni _______ Will this battery work? 1. _________________ 2. _________________ 3. _________________ 4. _________________ 5. _________________

Positive or Negative? 1. Li _Neg_Mg _Pos_ 1. Li _Neg_Mg _Pos_ 2. Fe _Pos_Ba _Neg_ 2. Fe _Pos_Ba _Neg_ 3. Au _Pos_Hg _Neg_ 3. Au _Pos_Hg _Neg_ 4. Sn _Neg_Pb _Pos_ 4. Sn _Neg_Pb _Pos_ 5. K _Neg_Ni _Pos_ 5. K _Neg_Ni _Pos_

Anode or Cathode? 1. Li ______Mg ______ 2. Fe _____Ba _______ 3. Au _____Hg _______ 4. Sn _____Pb _______ 5. K ______Ni _______ Draw an arrow that shows the electron flow: Draw an arrow that shows the electron flow: 1. Li ______Mg 2. Fe _____Ba 3. Au _____Hg 4. Sn _____Pb 5. K ______Ni

Anode or Cathode? 1. Li _Anode_Mg _Cathode_ 1. Li _Anode_Mg _Cathode_ 2. Fe _Cathode_Ba _Anode_ 2. Fe _Cathode_Ba _Anode_ 3. Au _Cathode_Hg _Anode_ 3. Au _Cathode_Hg _Anode_ 4. Sn _Anode_Pb _Cathode_ 4. Sn _Anode_Pb _Cathode_ 5. K _Anode_Ni _Cathode_ 5. K _Anode_Ni _Cathode_

Using the Activity Series on pg. 357 The FARTHER APART the 2 metals are on the activity series, the BIGGER the voltage of the battery. The FARTHER APART the 2 metals are on the activity series, the BIGGER the voltage of the battery. The CLOSER TOGETHER the 2 metals are on the activity series, the SMALLER the voltage of the battery. The CLOSER TOGETHER the 2 metals are on the activity series, the SMALLER the voltage of the battery. 1.Which battery would have the biggest voltage? How do you know? Li and Ba or Co and Au 2. Which battery would have the smallest voltage? How do you know? Fe and Ni OR Cu and Hg?

(Negative) (Positive) Zinc Sulfate solution Copper Sulfate solution Zinc Metal Copper Metal Oxidation Is Losing Reduction Is Gaining Electron

OIL RIG Oxidation Is Losing electrons Oxidation Is Losing electrons Ex. Mg  Mg electrons Ex. Mg  Mg electrons Always starts out neutral  Ends as a ion Always starts out neutral  Ends as a ion Reduction Is Gaining electrons Reduction Is Gaining electrons Ex. S electrons  S Ex. S electrons  S Always starts out as an ion  Ends neutral Always starts out as an ion  Ends neutral

Oxidation Half reaction of Li and Cu 1 st Identify the metal that is more likely to lose electrons…anode…oxidation (see activity series pg. 357) 1 st Identify the metal that is more likely to lose electrons…anode…oxidation (see activity series pg. 357) Li – higher on activity series 2 nd Find the # of electrons the element will lose based on its position on the periodic table (all transition elements will be considered +2…LEAD will also be a +2) 2 nd Find the # of electrons the element will lose based on its position on the periodic table (all transition elements will be considered +2…LEAD will also be a +2) Li loses 1 electrons since it is in the 1 st column of the periodic table…Li +1 3 rd Write the half reaction for the metal being oxidized (losing electrons) 3 rd Write the half reaction for the metal being oxidized (losing electrons) Li  1 e - + Li +1

Reduction half reaction Li and Cu 1 st Identify the metal that is more likely to gain electrons…cathode…reduction (see activity series pg. 357) 1 st Identify the metal that is more likely to gain electrons…cathode…reduction (see activity series pg. 357) Cu – lower on activity series 2 nd Find the # of electrons the element will gaining based on its position on the periodic (here we are assuming they have already lost electrons and are looking to gain those back) 2 nd Find the # of electrons the element will gaining based on its position on the periodic (here we are assuming they have already lost electrons and are looking to gain those back) ALWAYS starts off as an ion!! ALWAYS starts off as an ion!! Cu +2 (transition metal – in the “D” section of the table) 3 rd Write the half reaction for the element gaining electrons 3 rd Write the half reaction for the element gaining electrons Cu e -  Cu (notice it gains 2 negatives and becomes neutral) Cu e -  Cu (notice it gains 2 negatives and becomes neutral)

“We do” battery #2: Ag and Zn 1. Which element is the anode? ____________ Why? ________ 2. Which element is the cathode? ___________ Why? ________ 3. The electron will flow from ___________ to ________ because _____? 4. Which element is oxidation occurring? ______________ 5. Which element is reduction occurring? ______________ 6. Write the half reaction for the oxidation reaction that occurs in this battery: ________________________________ 7. Write the half reaction for the reduction reaction that occurs in this battery: ________________________________ 8. A second battery is made using copper instead of silver. Which battery would have the smaller voltage? _______________ How do you know? ____

“You do” battery #3: Pb and Fe 1. Which element is the anode? ____________ Why? ________ 2. Which element is the cathode? ___________ Why? ________ 3. The electron will flow from ___________ to ________ because _____? 4. Which element is oxidation occurring? ______________ 5. Which element is reduction occurring? ______________ 6. Write the half reaction for the oxidation reaction that occurs in this battery: ________________________________ 7. Write the half reaction for the reduction reaction that occurs in this battery: ________________________________ 8. A second battery is made using copper instead of lead. Which battery would have the larger voltage? _______________ How do you know? ____

REDOX Reactions Oxidation: Li  1 e - + Li +1 Oxidation: Li  1 e - + Li +1 Reduction: Cu e -  Cu Reduction: Cu e -  Cu Electrons MUST match!!! Electrons MUST match!!! Notice Li only loses 1 electron so the first reaction must be multiplied by 2 so electrons lost = electrons gained. Notice Li only loses 1 electron so the first reaction must be multiplied by 2 so electrons lost = electrons gained. Oxidation: (Li  1 e - + Li +1 ) X 2 = 2Li  2e - + 2Li +1 Oxidation: (Li  1 e - + Li +1 ) X 2 = 2Li  2e - + 2Li +1 Combine the two ½ equations: 2Li  + 2 e - + 2Li +1 Combine the two ½ equations: 2Li  + 2 e - + 2Li +1 Cu e -  Cu Cu e -  Cu 2Li + Cu +2  2Li +1 + Cu

“We Do” REDOX Reactions Make a battery out of Zinc and Copper Make a battery out of Zinc and Copper Electrons MUST match!!! Electrons MUST match!!! Oxidation: Zn  _____ + _____ Oxidation: Zn  _____ + _____ Reduction: Cu +2 + _____  ______ Reduction: Cu +2 + _____  ______ Combine the two ½ equations: Combine the two ½ equations:

“You Do” REDOX Reactions Make a battery out of Potassium and Tin Make a battery out of Potassium and Tin Electrons MUST match!!! Electrons MUST match!!! Oxidation: Oxidation: Reduction: Reduction: Combine the two ½ equations: Combine the two ½ equations:

(Negative) (Positive) Zinc Sulfate solution Copper Sulfate solution Zinc Metal Copper Metal Oxidation Is Losing Reduction Is Gaining Electron Zn  2e - + Zn +2 Cu e -  Cu