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Lecture Room Volt Meter with Bologna for a Salt Bridge

Procedure

• Pour 0.1M CuSO₄ into one 400mL beaker and 0.1M ZnSO₄ into another up to about the 300mL mark.

• Place a copper strip into the CuSO₄ solution and a zinc strip into the ZnSO₄ solution. Hook up double alligator clip leads from the zinc and copper strips to the leads on the lecture size volt meter. It should read zero volts.

• Hang a piece of filter paper soaked in saturated Na₂SO₄ over the ends of the beakers to form a salt bridge between the solutions

• With the meter set on center zero, measure the voltage. Switching leads shows direction of electron flow. Be sure the 3V module is in place.

• Hang a slice of bologna over the ends of the beakers, being sure that the bologna is immersed in both the CuSO₄ and ZnSO₄ solutions and measure the voltage. Hot dogs would work as well but they break when one tries to bend them over two beakers.

*Quantitative Chemistry, Jurg Waser