Celda de Concentración

Generación de voltaje a partir de diferencias de concentración

Electrochemistry Advanced (University) 45 min ~$18,00

Objetivo

Construir una celda de concentración usando semiceldas de cobre a diferentes concentraciones y verificar la predicción de la ecuación de Nernst para el potencial de celda.

Antecedentes

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.

Advertencias de seguridad

  • Copper sulfate is toxic
  • Wear gloves when handling solutions

EPP requerido

goggles gloves lab_coat

Materiales

  • 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

Equipamiento

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

Procedimiento

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

Resultados esperados

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.

Limpieza

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

Detalles

Categoría
Electrochemistry
Dificultad
Advanced (University)
Duración
45 min
Costo estimado
$18,00
Pasos
7
Materiales
3

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Frequently Asked Questions

What is the objective of Celda de Concentración?
Construir una celda de concentración usando semiceldas de cobre a diferentes concentraciones y verificar la predicción de la ecuación de Nernst para el potencial de celda.
How difficult is Celda de Concentración?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Celda de Concentración?
Key safety precautions include: Copper sulfate is toxic; Wear gloves when handling solutions.
What materials are needed for Celda de Concentración?
The main materials required are: Copper(II) sulfate (CuSO₄), Copper strips (2), Potassium nitrate salt bridge.
What results should I expect from Celda de Concentración?
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.