Author Question: Which reactions take place near the sensing electrode of an electrochemical NO analyzer? a. 2H2O ... (Read 64 times)

naturalchemist · **on:** Jul 16, 2018

Which reactions take place near the sensing electrode of an electrochemical NO analyzer?

a. 2H2O 4H+ + 4e + O2 c. 4NO + 2H2O + 2O2 4HNO3
b. O2 + 4H+ + 4e 2H2O d. NO + 2H2O HNO3 + 3H+ + 3e

Question 2

Which of the following gases affect the accuracy of NO/NO2 electrochemical monitors? 1. NH2 2. N2O 3. CO2 4. Carbon monoxide (CO) 5. Nitrogen (N2)

a. 1, 4, and 5 c. 2, 3, and 5
b. 1, 3, and 4 d. 3 and 4

fdliggud · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: D
An electrochemical NO analyzer consists of three electrodes immersed in an electrolyte solution that contains a highly conductive concentrated acid or alkali solution. The electrodes are sepa-rated from the gas sample to be analyzed by a semipermeable membrane. NO and NO2, from the unknown gas sample, diffuse across a semipermeable membrane and react with the electrolyte solution near the sensing electrode. This generates electrons in the oxidation reaction: NO + 2H2O HNO3 + 3H+ + 3e.

Answer to Question 2

ANS: B
The accuracy of NO/NO2 electrochemical monitors can be altered by the presence of background gasessuch as CO2, CO, and NH2that have lower oxidation potentials than the sensor poten-tial.