You are on your dream vacation at the beach when a major storm kn...

Question

You are on your dream vacation at the beach when a major storm knocks out the power for days. Your cell phone is dead, and you want to make a battery to charge it. You find the following materials in the beach house: blue stone algaecide for pools, which can be used to make a 1.0 M Cu2+ solution; alum in the kitchen, which can be used to make a 1.0 M Al3+ solution; aluminum foil; copper wire; and bologna, which can be used as a salt bridge. (a) What are the half-reactions and overall reaction in the battery? (b) Draw a diagram using beakers, a voltmeter, and salt bridge to show how a battery can be constructed. Label the anode, cathode, and direction of electron flow.

Accepted Answer

Step 1: Identify the half-reactions for the redox process. For the copper half-reaction, $$Cu^{2+} + 2e$$^- \rightarrow Cu(s), and for the aluminum half-reaction, Al(s) \rightarrow $$Al^{3+} + 3e^-.. $$Step 2: Balance the electrons in the half-reactions. Multiply the copper half-reaction by 3 and the aluminum half-reaction by 2 to balance the electrons exchanged.. Step 3: Combine the balanced half-reactions to write the overall cell reaction. Ensure that the number of electrons lost in the oxidation half-reaction equals the number of electrons gained in the reduction half-reaction.. Step 4: Construct a diagram of the galvanic cell. Use two beakers, one containing the $$Cu^{2+}$$ solution with a copper wire (cathode) and the other containing the $$Al^{3+}$$ solution with aluminum foil (anode). Connect the electrodes with a voltmeter and use bologna as a salt bridge between the solutions.. Step 5: Label the anode and cathode in the diagram. Indicate the direction of electron flow from the anode (Al) to the cathode (Cu) through the external circuit, and the flow of ions through the salt bridge to maintain charge balance.

Key Concepts

Electrochemical Cells

Half-Reactions

Salt Bridge