(a) Name the device used for producing an electric current from a chemical (b) Copy and complete the table below. Electrolyte Product at the anode (carbon) ...
Question 1 Report
(a) Name the device used for producing an electric current from a chemical
(b) Copy and complete the table below.
| Electrolyte | Product at the anode (carbon) | Product at the cathode (carbon) |
| Dilute \( \mathrm{NaCl}_{(aq)} \) Concentrated \( \mathrm{NaCI}_{(aq)} \) |
Answer Details
(a) The device used for producing an electric current from a chemical reaction is an electrochemical cell (also called a galvanic or voltaic cell, or simply a chemical cell).
(b) Completed table
Reasoning:
- In dilute \( NaCl_{(aq)} \) the solution is mostly water. At the anode, \( OH^- \) is discharged in preference to the dilute \( Cl^- \), giving oxygen. At the cathode, \( H^+ \) is discharged in preference to \( Na^+ \) (sodium is high in the electrochemical series), giving hydrogen.
- In concentrated \( NaCl_{(aq)} \) the high concentration of \( Cl^- \) causes chloride to be discharged at the anode instead of \( OH^- \), giving chlorine. Hydrogen is still liberated at the cathode.
| Electrolyte | Product at the anode (carbon) | Product at the cathode (carbon) |
|---|---|---|
| Dilute \( NaCl_{(aq)} \) | Oxygen, \( O_2 \) | Hydrogen, \( H_2 \) |
| Concentrated \( NaCl_{(aq)} \) | Chlorine, \( Cl_2 \) | Hydrogen, \( H_2 \) |
Electrode half-equations: at the cathode \( 2H^+ + 2e^- \rightarrow H_2 \); at the dilute anode \( 4OH^- \rightarrow O_2 + 2H_2O + 4e^- \); at the concentrated anode \( 2Cl^- \rightarrow Cl_2 + 2e^- \).
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