Question

Zirconia analyzer is used to measure

• A. oxygen
• B. nitrogen
• C. CO
• D. carbon dioxide

Hint:

Zirconia oxide probes are widely used in automotive exhaust systems (lambda sensors) and power plant boiler chimneys to monitor oxygen levels for optimizing combustion.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks about the target gas measured by a Zirconia analyzer.

Step 2: Detailed Explanation:

• A Zirconia analyzer is a solid-state electrochemical sensor designed to measure the concentration of oxygen ($O_2$) in a gas stream.

• It consists of a tube or disc made of zirconium dioxide ($ZrO_2$) ceramic stabilized with yttria, coated with thin porous platinum electrodes on both sides.

• At high temperatures (typically above $600^{\circ}\text{C}$), the zirconia lattice becomes highly conductive to oxygen ions ($O^{2-}$).

• When there is a difference in oxygen concentration between the reference side (usually ambient air, $20.9\%\ O_2$) and the process gas side, a voltage (EMF) is generated across the platinum electrodes.

• This voltage is governed by the Nernst Equation:
\[ E = \frac{RT}{4F} \ln\left(\frac{P_{O_2,\text{ ref}}}{P_{O_2,\text{ process}}}\right) \]
• By measuring this voltage, the concentration of oxygen in the process gas can be determined with high precision.

Step 3: Final Answer:
The Zirconia analyzer is used to measure oxygen.