Oxidation-Reduction Reactions1. Review the Activity Series we usedwith single replacement reactions2. Oxidation is the loss of electrons3. Reduction is the gain of electrons4. The Reducing Agent is oxidized5. The Oxidizing Agent is reduced
Calculating Oxidation Number The ﬁrst step in better understanding redox reactions is the determination of the oxidation # of each element in a compound. (+2) (+1) (-2) H 2 0 When determining oxidation numbers, look for oxygen (-2) or hydrogen (+1). Group I and II metals are also a good bet (+1 or +2). Halogens like ﬂuorine, chlorine, bromine, and iodine (usually –1) are consistent, especially if paired with a metal.
Determine the oxidation numbers of the following:MnO4-1 NO3-1 H2SO4 AgNO3HClO NaCl BaF2 K2Cr2O7
A Few Reactions...Cu(NO3)2 + Ni Ni(NO3)2 + CuPb + PbO2 + H2SO4 PbSO4 + H2ONa+ H2O NaOH + H2 1. Put oxidation #’s above each element 2. Find the element oxidized (lose electrons) 3. Find the element reduced (gain electrons) Voltaic Cell
Batteries and Galvanic Cells:Applications of RedoxReactions. •Fuel cells for cars •Power for personal electronic Lithium ion batteries devices (cell phones, etc)
The Anatomy of a Battery Do a diagram of a battery made from aluminum and silver. 1. Electrodes 2. Solutions 3. Salt bridge 4. Direction of e- ﬂow 5. Voltage 6. Label anode and cathode, as well as the +/- electrodes Importance of the salt bridge- as Al Al+3 + 3e- …. the electrons leave the anode and go to the cathode. This leaves a buildup of Al+3 ions that could interfere with the ﬂow of electrons to the cathode. The salt bridge allows NO3-1 ions to ﬂow from the cathode to the anode to balance the build up of Al+3.