A sodium selective electrode increased in voltage by 59.16 mV when the sodium cation concentration was increased by a factor of 10.A S²⁻ selective electrode measured a decrease of 29.58 mL when the sulfide concentration increased by a factor of 10.Why?
I Cations always increase the measured potential by n × 59.16 mV where n is the charge on the cation.
II Anions always decrease the measured potential by n × 59.16 mV where n is the charge on the anion.
III Cations always increase the measured potential by where n is the charge on the cation.
IV Anions always decrease the measured potential by where n is the charge on the anion.

Question

A sodium selective electrode increased in voltage by 59.16 mV when the sodium cation concentration was increased by a factor of 10.A S²⁻ selective electrode measured a decrease of 29.58 mL when the sulfide concentration increased by a factor of 10.Why?
I Cations always increase the measured potential by n × 59.16 mV where n is the charge on the cation.
II Anions always decrease the measured potential by n × 59.16 mV where n is the charge on the anion.
III Cations always increase the measured potential by

A sodium selective electrode increased in voltage by 59.16 mV when the sodium cation concentration was increased by a factor of 10.A S<sup>2</sup><sup>−</sup> selective electrode measured a decrease of 29.58 mL when the sulfide concentration increased by a factor of 10.Why? I Cations always increase the measured potential by n × 59.16 mV where n is the charge on the cation. II Anions always decrease the measured potential by n × 59.16 mV where n is the charge on the anion. III Cations always increase the measured potential by where n is the charge on the cation. IV Anions always decrease the measured potential by where n is the charge on the anion. A) II and III B) III and IV C) I and II D) I and IV E) None of the statements explain the behavior.

where n is the charge on the cation.
IV Anions always decrease the measured potential by

where n is the charge on the anion.

Quizplus · Accepted Answer

The given statement III corresponds to the Nernst equation that relates the measured potential to the concentration of the ion. Thus, the increase in voltage is proportional to the logarithm of the concentration ratio between two solutions. As the concentration of the sodium cation increases by a factor of 10, it leads to an increase in voltage of 59.16 mV. Similarly, for statement IV, the given equation corresponds to the Nernst equation for anion selective electrodes, where an increase in concentration decreases the voltage. Therefore, statement B is the best choice that explains the behavior observed for both the sodium and sulfide selective electrodes.

A Sodium Selective Electrode Increased in Voltage by 59