Experiment 17

Electrochemical Cells and Thermodynamics

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In Lab

• Work in groups of 2

• Each student does their own graph and calculations

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Modifications to Experiment

• The reactants are:Fe2+

(aq)

Cu2+(aq)

Fe(s)

Cu(s)

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Modifications to Experiment

Use the porous cup instead of the inverted U-tube.

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Porous Cup250 mL Beaker

Voltmeter

Three (or two) number scales are shown, use the 0 to 3 Volt scale (or 0 to 5 Volt scale)

Use the red 3 or 5 lead, not the red 15.

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Voltmeter

Anode to the (-) lead and the cathode to the (+) lead.

The alligator clips can clip onto the lead posts if the plastic coverings are as far up as they can go.

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Final Setup

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Handling of Porous Cup

• Please do not expose the cup to drastic temperature changes. Have the cup change temperature gradually.

• For cold temperatures, not too cold (5°C)

• Separate the porous cup and beaker; put each into an ice bath

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Calculations

ΔG = - nFE to calculate ΔG

ΔG = - RT lnKeq to calculate Keq

ΔS Graph ΔG vs. Temp (Kelvin), find slope

ΔH Rearrange ΔG = ΔH - T ΔS to solve for ΔH

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Clean-Up

• Please rinse the porous cup several times with tap water, then twice with deionized water.

• Clean the 250 mL beaker with soap and rinse well with tap water, then deionized water.

• Soak the porous cup in deionized water that is in the 250 mL beaker. Soak for several minutes.

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