Electrochemistry and Chemical Sensors

Question 1

1. Ion-selective electrodes measure electrical potential difference across a membrane using the principles of:

a. coulometry.
b. potentiometry.
c. amperometry.
d. conductivity

Answer 1

b. potentiometry.

Question 2

2. An optical sensor used in analytical instruments to measure pH, blood gases, and electrolytes is referred to as
   a(n):

a. potientiometer.
b. optode.
c. affinity-type sensor.
d. coulometer.

Answer 2

b. optode.

Question 3

3. Voltammetry/amperometry measurements are based on
   which of the following electrochemical cell types?

a. Ion-selective electrode cells
b. Galvanic electrochemical cells
c. Electromotive force cells
d. Electrolytic electrochemical cells

Answer 3

d. Electrolytic electrochemical cells

Question 4

4. An affinity-based biosensor is one in which:

a. the biologic element recognizes the analyte on the basis of its binding to an immobilized substance.
b. the fluorescence of a solution is coupled to an enzyme-catalyzed reaction.
c. the biologic element reacts with an ion-selective
electrode that is used as a potentiometric transducer.
d. an electron acceptor is used to form a colored reaction product.

Answer 4

a. the biologic element recognizes the analyte on the basis of its binding to an immobilized substance.

Question 5

5. A voltmeter that measures the potential across an electrochemical cell (between the two electrodes) is referred
   to as a:

a. conductometer.
b. amperometer.
c. direct-reading potentiometer.
d. redox meter

Answer 5

c. direct-reading potentiometer.

Question 6

6. Membrane potentials caused by the permeability of certain types of membranes to selected anions or cations are
   measured by which type of electrode?

a. Ion-selective electrode
b. Saturated calomel electrode
c. Platinum electrode
d. Gas-sensing electrode

Answer 6

a. Ion-selective electrode

Question 7

7. The maximum difference in potential between the two
   electrodes in an electrochemical cell obtained with the
   current at zero is the definition of:

a. electrical potential.
b. electromotive force.
c. electrochemical gradient.
d. Nernst equation

Answer 7

b. electromotive force.

Question 8

8. In this type of measurement, a constant current is applied
   to a solution, and a substance in that solution is changed
   to a different state through oxidation or reduction. The
   time it takes for this to occur is measured. This electrochemical technique is called:

a. amperometry.
b. voltammetry.
c. potentiometry.
d. coulometry

Answer 8

d. coulometry

Question 9

9. The measurement of ions by direct potentiometry provides a value for the concentration of free, unbound ion
   in solution that is called the ionic:

a. force.
b. potential.
c. activity.
d. action.

Answer 9

c. activity.

Question 10

10. The predominant class of potentiometric electrodes used
    in the clinical laboratory is the:

a. gas-sensing electrode.
b. glass membrane electrode.
c. coulometric electrode.
d. polymer membrane ion-selective electrode.

Answer 10

d. polymer membrane ion-selective electrode.