Célula de Concentração

Geração de tensão a partir de diferenças de concentração

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

Objetivo

Construir uma célula de concentração usando semicélulas de cobre em diferentes concentrações e verificar a previsão da equação de Nernst para o potencial de célula.

Contexto

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.

Avisos de segurança

  • Copper sulfate is toxic
  • Wear gloves when handling solutions

EPI necessário

goggles gloves lab_coat

Materiais

  • 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

Equipamentos

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

Procedimento

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.

Limpeza

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

Detalhes

Categoria
Electrochemistry
Dificuldade
Advanced (University)
Duração
45 min
Custo estimado
$18,00
Passos
7
Materiais
3

Mais experimentos

Bateria de Limão 20 min Construção da Célula de Daniell 45 min Eletrólise da Água 40 min Eletrólise do Sulfato de Cobre 50 min Galvanoplastia com Cobre 60 min Medição do Potencial de Célula Voltaica 60 min Métodos de Prevenção de Ferrugem 30 min Verificação da Série de Atividade 30 min

Frequently Asked Questions

What is the objective of Célula de Concentração?
Construir uma célula de concentração usando semicélulas de cobre em diferentes concentrações e verificar a previsão da equação de Nernst para o potencial de célula.
How difficult is Célula de Concentração?
This experiment is rated as Advanced (University). It takes approximately 45 minutes to complete.
What safety precautions are needed for Célula de Concentração?
Key safety precautions include: Copper sulfate is toxic; Wear gloves when handling solutions.
What materials are needed for Célula de Concentração?
The main materials required are: Copper(II) sulfate (CuSO₄), Copper strips (2), Potassium nitrate salt bridge.
What results should I expect from Célula de Concentração?
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.