Question 1

Potentiometric measurements are based on galvanic electrochemical cells.These types of cells consist of:&#10;A) two inert metal electrodes to which an electrical potential is applied.&#10;B) two electron or metallic conducting electrodes that are connected by an electrolyte solution that conducts ions.&#10;C) a biological recognition element and a physicochemical transducer,often an electrochemical or optical device.&#10;D) a polarizable working electrode to which an external voltage is applied with the resulting cathodic or anodic current of the cell being monitored.

Accepted Answer

Potentiometric measurements involve measuring the electrical potential difference between two electrodes in an electrochemical cell. The electrochemical cell consists of two conducting electrodes that are connected by an electrolyte solution. In this setup, there is no need for an external voltage to be applied, as the potential difference arises due to the chemical reactions occurring at the electrodes. Therefore, option B is the correct choice. Option A is incorrect because the electrodes are not inert in potentiometric measurements. Option C is incorrect because it describes a biosensor setup. Option D is incorrect because the working electrode is not polarizable in potentiometric measurements.

Question 2

A commonly used electrode also used as an internal reference electrode in ion-selective electrode measurements is which one of the following?&#10;A) Silver/silver chloride&#10;B) Mercury vapor&#10;C) Platinum&#10;D) Gas permeable

Accepted Answer

Silver/silver chloride electrodes are commonly used as reference electrodes in many electrochemical measurements, including ion-selective electrode measurements. The electrode potential of the silver/silver chloride electrode is stable and reproducible, making it a reliable internal reference electrode.

Question 3

In an optical sensing (optode)system for the measurement of PO₂ using fluorescence,what is being measured? A) The increase in the intensity of the oxygen's natural fluorescence B) The amount of charge passing between the optical sensing electrodes,which is directly proportional to the PO₂ C) The decrease in intensity of an organic dye's fluorescence in the presence of molecular oxygen,which is proportional to the PO₂ D) The ability of oxygen in solution to carry current under the influence of a potential difference

Accepted Answer

In an optical sensing (optode) system that uses fluorescence, a fluorescent dye is typically used as the oxygen-sensitive indicator. When excited by a light source, the dye emits fluorescence which can be detected and measured using a photodetector. The presence of molecular oxygen causes the fluorescence of the dye to decrease, and the extent of this decrease is directly proportional to the PO₂. Therefore, option C is the correct answer. Option A is incorrect because oxygen does not have natural fluorescence. Option B and D are incorrect because they do not relate to fluorescence measurement.

Question 4

Incorporation of _____,a neutral antibiotic,into a polyvinyl chloride membrane allows for the manufacture of an ion-selective electrode that is highly selective for potassium.&#10;A) tetracycline&#10;B) nonactin&#10;C) valinomycin&#10;D) erythromycin

Accepted Answer

Valinomycin is a neutral antibiotic that forms a complex with potassium ions, making it highly selective for potassium. When incorporated into a polyvinyl chloride membrane, it can be used to create an ion-selective electrode specifically for potassium. Tetracycline, erythromycin, and nonactin do not have the same potassium-selective properties as valinomycin.

Question 5

The type of ion-selective electrode mentioned in the preceding question is in a category of electrodes referred to as _____ electrodes.&#10;A) glass&#10;B) inert metal&#10;C) polymer membrane&#10;D) participating metal

Accepted Answer

The ion-selective electrode mentioned in the preceding question is referred to as a polymer membrane electrode, as it uses a polymer membrane as the selective membrane to detect specific ions.

Question 6

A PCO₂ electrode: A) uses coulometric titration to measure the absolute level of CO₂ in blood through the combination of CO₂ with water. B) is a potentiometric cell in which carbon dioxide gas from the sample diffuses through a membrane and forms carbonic acid. C) measures the ability of carbonate ions in solution to carry current under the influence of a potential difference. D) utilizes a gas-permeable membrane to detect CO₂ with very high selectivity over other easily reduced species that might be present in a given sample.

Accepted Answer

A PCO₂ electrode is a potentiometric cell where CO₂ gas diffuses through a membrane and forms carbonic acid, which changes the pH and is measured to determine CO₂ levels.

Question 7

Measurement of pH involves which kind of electrode? A) Hydrogen ion-selective electrode B) Hydrogen redox electrode C) Gas permeable PCO₂ electrode D) Voltammetric hydrogen electrode

Accepted Answer

The answer of Measurement of pH involves which kind of...

Question 8

Which one of the following is not measured with an enzyme-based biosensor,with a light sensing fiber optic probe? A) Cholesterol B) PO₂ C) Bilirubin D) DNA segments

Accepted Answer

DNA segments are typically measured using techniques like PCR or sequencing, not with enzyme-based biosensors or light sensing fiber optic probes.

Question 9

The measurement of the voltage difference between two half-cells immersed in solution is referred to as:&#10;A) coulometry.&#10;B) turbidimetry.&#10;C) amperometry.&#10;D) potentiometry.

Accepted Answer

The measurement of the voltage difference between two half-cells immersed in solution is referred to as potentiometry. Coulometry involves the measurement of the amount of electricity transferred during a chemical reaction, Turbidimetry is the measurement of the amount of light scattered by a suspension, and Amperometry involves the measurement of electric current flow.

Question 10

Which one of the following voltage potentials occurs as the result of chemical equilibrium involving electron transfer reactions?&#10;A) Electrode potential&#10;B) Positive potential&#10;C) Hydrogen potential&#10;D) Redox potential

Accepted Answer

Redox potential is the voltage potential that occurs as a result of chemical equilibrium involving electron transfer reactions (redox reactions). It represents the tendency of a chemical species to acquire or lose electrons, and is a measure of the availability of electrons for redox reactions. Electrode potential refers to the potential difference between an electrode and a solution, while positive potential and hydrogen potential are not directly related to electron transfer reactions.

Question 11

Which of the following conditions are among the requirements for a Nernst equilibrium potential to exist for a given charged ion species across a semipermeable membrane as in an ion-selective electrode?

A) The semipermeable membrane must be permeable to many ion species.
B) A concentration gradient for a given charged ion species must exist across that membrane.
C) If a membrane is permeable to two different ion species,then the ion activity of both species can be measured.
D) The membrane potential across a semipermeable membrane must be constantly changing.

Accepted Answer

The answer of Which of the following conditions are among...

Question 12

A biosensor that uses both enzyme detection and an ion-specific electrode could be examining:&#10;A) urea using urease and the production of ammonium ions.&#10;B) glucose using glucose oxidase and the production of biocarbonate ions.&#10;C) cholesterol using cholesterol oxidase with production of fluorescent cations.&#10;D) bilirubin using bilirubin oxidase and the production of hydrogen ions.

Accepted Answer

The answer of A biosensor that uses both enzyme detection...

Question 13

A commonly used glass electrode that is used as a reference electrode in pH measurements is the _____ electrode.&#10;A) calomel&#10;B) mercury vapor&#10;C) silver/silver chloride&#10;D) platinum

Accepted Answer

The answer of A commonly used glass electrode that is...

Question 14

A physician is concerned about an emphysema patient's PO₂ level and wants to determine it in this patient's blood.Which one of the following would be best used to determine PO₂? A) Ion-selective electrode B) Coulometric method C) Amperometric method D) Conductivity-based measurement

Accepted Answer

The answer of A physician is concerned about an emphysema...

Question 15

An electrochemical technique used to measure chloride in serum or plasma is:&#10;A) conductometry.&#10;B) amperometry.&#10;C) coulometry.&#10;D) voltammetry.

Accepted Answer

The answer of An electrochemical technique used to measure chloride...

Deck 10: Electrochemistry and Chemical Sensors