UNDERSTANDINGS

• R3.2.1—Oxidation and reduction can be described in terms of electron transfer, change in oxidation state, oxygen gain/loss or hydrogen loss/gain.

  • Deduce oxidation states of an atom in a compound or an ion.

  • Identify the oxidized and reduced species and the oxidizing and reducing agents in a chemical reaction.

• R3.2.2—Half-equations separate the processes of oxidation and reduction, showing the loss or gain of electrons.

  • Deduce redox half-equations and equations in acidic or neutral solutions.

• R3.2.3—The relative ease of oxidation and reduction of an element in a group can be predicted from its position in the periodic table.

• The reactions between metals and aqueous metal ions demonstrate the relative ease of oxidation of different metals.

  • Predict the relative ease of oxidation of metals.

  • Predict the relative ease of reduction of halogens.

  • Interpret data regarding metal and metal ion reactions.

• R3.2.4—Acids react with reactive metals to release hydrogen.

  • Deduce equations for reactions of reactive metals with dilute HCl and H2SO4 .

• R3.2.5—Oxidation occurs at the anode and reduction occurs at the cathode in electrochemical cells.

  • Identify electrodes as anode and cathode, and identify their signs/polarities in voltaic cells and electrolytic cells, based on the type of reaction occurring at the electrode.

• R3.2.6—A primary (voltaic) cell is an electrochemical cell that converts energy from spontaneous redox reactions to electrical energy.

  • Explain the direction of electron flow from anode to cathode in the external circuit, and ion movement across the salt bridge.

• R3.2.7—Secondary (rechargeable) cells involve redox reactions that can be reversed using electrical energy.

  • Deduce the reactions of the charging process from given electrode reactions for discharge, and vice versa.

• R3.2.8—An electrolytic cell is an electrochemical cell that converts electrical energy to chemical energy by bringing about non-spontaneous reactions.

  • Explain how current is conducted in an electrolytic cell.

  • Deduce the products of the electrolysis of a molten salt.

• R1.3.5—A fuel cell can be used to convert chemical energy from a fuel directly to electrical energy.

  • Deduce half-equations for the electrode reactions in a fuel cell.

MAKING CONNECTIONS