Konzentrationselement

Spannungserzeugung durch Konzentrationsunterschiede

Electrochemistry Advanced (University) 45 Min. ~$18,00

Ziel

Ein Konzentrationselement aus Kupferhalbzellen unterschiedlicher Konzentration aufbauen und die Vorhersage der Nernst-Gleichung für das Zellpotenzial überprüfen.

Hintergrund

A concentration cell generates voltage from the difference in concentration between two otherwise identical half-cells. According to the Nernst equation, the EMF depends on the logarithm of the concentration ratio. This experiment demonstrates that even without different metals, a potential difference arises from entropy-driven mixing.

Sicherheitswarnungen

  • Copper sulfate is toxic
  • Wear gloves when handling solutions

Erforderliche PSA

goggles gloves lab_coat

Materialien

  • Copper(II) sulfate (CuSO₄) (200 mL total)
    Prepare 0.01M and 1M solutions
  • Copper strips (2) (2 pieces)
    Identical, sanded clean
  • Potassium nitrate salt bridge (1)
    Saturated KNO₃ in agar

Ausrüstung

Two 250 mL beakers High-impedance voltmeter Wires with alligator clips Sandpaper Volumetric flasks

Durchführung

1

Prepare two CuSO₄ solutions: 100 mL of 1.0M and 100 mL of 0.01M.

5 Min. Wear gloves
2

Sand both copper strips until shiny and rinse with distilled water.

3 Min.
3

Pour the dilute (0.01M) CuSO₄ into one beaker and the concentrated (1.0M) into the other.

2 Min.
4

Place one copper strip in each beaker. Connect with the salt bridge.

3 Min.
5

Connect the voltmeter. The dilute side is the anode (negative terminal). Measure the EMF.

5 Min.
6

Calculate the predicted EMF using the Nernst equation: E = (RT/nF) ln(C_high/C_low) = (0.0257/2) ln(100) = 0.059 V at 25°C.

5 Min.
7

Compare measured and theoretical values. Discuss sources of deviation.

5 Min.

Erwartete Ergebnisse

The cell should produce approximately 0.05-0.06 V. The Nernst equation predicts E = (0.02569 V / 2) x ln(1.0/0.01) = 0.059 V at 25°C. Measured values may be slightly lower due to junction potentials.

Aufräumen

Dispose of copper sulfate waste in designated containers. Rinse and store copper strips. Clean salt bridge.

Details

Kategorie
Electrochemistry
Schwierigkeit
Advanced (University)
Dauer
45 Min.
Geschätzte Kosten
$18,00
Schritte
7
Materialien
3

Weitere Experimente

Aufbau der Daniell-Zelle 45 min Elektrolyse von Kupfersulfat 50 min Elektrolyse von Wasser 40 min Galvanisierung mit Kupfer 60 min Messung des galvanischen Zellpotenzials 60 min Methoden zum Rostschutz 30 min Verifikation der Aktivitätsreihe 30 min Zitronenbatterie 20 min

Frequently Asked Questions

What is the objective of Konzentrationselement?
Ein Konzentrationselement aus Kupferhalbzellen unterschiedlicher Konzentration aufbauen und die Vorhersage der Nernst-Gleichung für das Zellpotenzial überprüfen.
How difficult is Konzentrationselement?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Konzentrationselement?
Key safety precautions include: Copper sulfate is toxic; Wear gloves when handling solutions.
What materials are needed for Konzentrationselement?
The main materials required are: Copper(II) sulfate (CuSO₄), Copper strips (2), Potassium nitrate salt bridge.
What results should I expect from Konzentrationselement?
The cell should produce approximately 0.05-0.06 V. The Nernst equation predicts E = (0.02569 V / 2) x ln(1.0/0.01) = 0.059 V at 25°C. Measured values may be slightly lower due to junction potentials.