Potentiometric pH titration (phosphoric acid in soft drinks) with CobraSMARTsense

Principle

The cell voltage and the Galvani voltage of the electrodes of a galvanic cell are dependent upon the concentration of the ions involved in the potential forming process. Thus, conclusions can be made about the concentration of the ions to be investigated from the measured cell voltage at a constant potential of a suitable reference electrode (potentiometric titration).

Benefits

• Simplified implementation: all pre-settings already prepared
• Extensive automation of the experiment allows concentration on the learning objectives
• Drop counter optimizes the experimental procedure

Tasks

Using the Cobra4-System, measure the change in the cell voltage in the titration of a sample of a carbonated beverage (Cola) containing phosphoric acid (E338) with 0.1 molar sodium hydroxide solution and calculate the beverage's phosphoric acid content from the consumption of the standard solution.

Learning objectives

• Galvanic cell
• Types of electrodes
• Galvani voltage
• Cell voltage
• Nernst equation
• Potentiometry
• Volumetry
  

This experiment requires a computer. Software provided.