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Difficulty: MediumAnalyzing Experimental Procedures and Apparatus

Experiment 1
Students set up an electrolysis apparatus to produce hydrogen gas (H2H_2) and chlorine gas (Cl2Cl_2) from an aqueous sodium chloride (NaClNaCl) solution. The apparatus consisted of a U-shaped glass tube separated into two distinct chambers by a porous ceramic diaphragm placed at the bottom bend. Platinum electrodes connected to a direct-current power source were immersed in each chamber. Chamber 1 contained the cathode, where H2H_2 gas and hydroxide ions (OH−OH^-) were generated. Chamber 2 contained the anode, where Cl2Cl_2 gas was generated.

Based on the described experimental setup, what is the primary procedural function of the porous ceramic diaphragm between Chamber 1 and Chamber 2?

  1. To allow the migration of ions between chambers to complete the electrical circuit while preventing the bulk mixing of produced chemical products.Answer
  2. B
    To serve as the primary source of electrons that reduces hydrogen ions into hydrogen gas at the cathode interface.
  3. C
    To measure the volumetric flow rate of chlorine gas evolving from the anode in real time.
  4. D
    To convert the direct current supplied by the power source into an alternating current inside the electrolyte solution.

Answer

The primary procedural function of the porous ceramic diaphragm is to permit ion migration across chambers to complete the electrical circuit while preventing bulk liquid mixing and unwanted reactions between the electrolysis products.
In an electrochemical cell, a complete circuit requires ionic movement through the electrolyte solution. The porous ceramic diaphragm provides a pathway for ions to travel between Chamber 1 and Chamber 2 while maintaining a physical barrier that prevents bulk fluid mixing and secondary chemical reactions between hydrogen/hydroxide ions and chlorine gas.

Step-by-Step Solution

1
Identify the components of the electrolysis apparatus described in the passage.
The setup consists of two chambers connected at the bottom via a porous ceramic diaphragm, with platinum electrodes submerged in aqueous NaCl connected to a DC power supply.
Understanding component layout is essential for analyzing apparatus function.
2
Analyze the physical and chemical requirements of an electrochemical cell operating under continuous electrolysis.
An unbroken electrical circuit requires charge carriers to flow: electrons travel through external wires, while ions must move through the solution between the anode and cathode.
Without ion movement, charge separation would build up and stop the reaction.
3
Determine the functional role of a porous barrier in preventing secondary chemical reactions.
The microscopic pores allow small ions to pass through while preventing fluid turbulence and mass transport of dissolved products (OH−OH^- and Cl2Cl_2) across chambers.
Mixing OH−OH^- with Cl2Cl_2 would produce secondary products (such as hypochlorite) instead of pure chlorine gas.

Key Concept

Function of semi-permeable and porous diaphragms in electrochemical apparatus setups
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Topics

Analyzing Experimental Procedures and Apparatus

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