Voltage Change: Potentiometric Titration Curves Quiz

Traditional indicators rely on a visible color change, which can be obscured in dark or cloudy samples. Potentiometry measures electrical potential, allowing for accurate analysis of solutions where visual detection is impossible.

The Nernst Equation relates the reduction potential of an electrochemical cell to the standard electrode potential, temperature, and effective concentrations of the chemical species undergoing oxidation and reduction.

This is true. On a plot of Potential versus Volume, the steepest part of the curve represents the rapid change in ion concentration at the equivalence point.

The first derivative represents the rate of change of potential. The maximum value of this plot aligns exactly with the steepest part of the original titration curve, making it easier to pinpoint the exact equivalence volume.

The second derivative plot shows a zero crossing. The point where the value passes through zero between a positive peak and a negative peak provides the most precise mathematical location for the equivalence point.

A reference electrode, such as a Saturated Calomel Electrode or Silver/Silver Chloride electrode, provides a stable, known potential against which the changing potential of the indicator electrode is measured.

This is false. Potentiometry is highly versatile and is used extensively for redox titrations, precipitation titrations using ion selective electrodes, and complexometric titrations.

A glass pH electrode is the standard indicator electrode for acid base titrations. Its potential varies linearly with the log of the hydrogen ion activity, allowing for the monitoring of pH changes as the titrant is added.

A stirrer ensures the solution is homogeneous, the meter records the electrical data, and the electrodes sense the chemical change. High heat from a burner is generally not required and could damage sensitive electrodes.

Near the equivalence point, the potential changes very rapidly with very small additions of titrant. Taking smaller volume readings in this region is necessary to construct an accurate curve and perform derivative analysis.

This is true. The inflection point mathematically corresponds to the equivalence point in symmetric titration curves, where the first derivative is at a maximum and the second derivative is zero.

If the solution is not well mixed or if the salt bridge junction of the reference electrode is blocked, the electrical circuit may be inconsistent, leading to erratic voltage readings on the meter.

Potentiometry is applicable to any reaction involving a change in the activity of an ion for which a suitable indicator electrode exists. Nuclear decay is a subatomic process and is not analyzed via titration.

A platinum electrode is chemically inert and does not participate in the reaction, but it serves as a surface for electron transfer, allowing it to sense the redox potential of the solution.

This is true. Because potentiometry measures a physical property of the analyte directly rather than relying on an external indicator color change, the end point and equivalence point are effectively identical for practical purposes.