Lec 6 - Electrochemistry

Question 1

A term used when chemical energy is converted to electrical current in a galvanic cell or electrolytic cell.

Answer 1

Electrochemistry

Question 2

The measurement of electrical signals associated with chemical systems that are incorporated in an electrochemical cell

Answer 2

Electrochemistry (2)

Question 3

An electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell.

Answer 3

Galvanic cell

Question 4

Loss of electrons

Answer 4

Oxidation

Question 5

Gain of electrons

Answer 5

Reduction

Question 6

Site of reduction

Answer 6

Cathode

Question 7

Site of oxidation

Answer 7

Anode

Question 8

An electrochemical cell where electric current causes the transfer of electrons in a redox reaction.

Answer 8

Electrolytic cell

Question 9

___ cell uses the transfer of electrons in redox reactions to supply an electrical circuit.

Whereas, ___ cell requires current to cause the transfer of electrons in a redox reaction.

Answer 9

GALVANIC cell ___ the transfer of electrons in redox reactions to supply an electrical circuit.

Whereas, ELECTROLYTIC cell requires current to ___ the transfer of electrons in a redox reaction.

Question 10

A process wherein electricity is used to make a chemical change.

Answer 10

Electrolysis

Question 11

A basic category of Electrochemical Technique:

• measures voltage as volts
• measurement of a cell potential under equilibrium conditions.
• uses galvanic cell principle

Answer 11

Potentiometry

Question 12

A basic category of Electrochemical Technique:

• measures current
• comprises the combination of voltage with amperometry.

Answer 12

Voltammetry

Question 13

Voltammetry:

Voltage is ___?

Answer 13

Applied to the electrolytic cell consisting of 2 or 3 electrodes dipped into the solution.

Question 14

Voltammetry:

Amperometry is ___?

Answer 14

The measurement of electric current flowing through the cell

Question 15

Potentiometry (principle)

Answer 15

Measurement of electrical potential between 2 electrodes in a solution, and comparing those 2 to each other.

Question 16

Potentiometric methods are best suited for measurement of ions such as __, __, and __.

Answer 16

Sodium, potassium and chloride

Question 17

Types of potentiometric electrodes

Answer 17

Redox electrodes,
Ion-selective electrodes,
pCO2 electrodes

Question 18

It measures the current in an electrochemical cell as a function of the applied potential.

Answer 18

Voltammetry

Question 19

Types of voltammetry

Answer 19

Polarography,
Amperometry,
Stripping voltammetry,
Hydrodynamic voltammetry

Question 20

Amperometry (Principle)

Answer 20

Measurement of current through an electrochemical cell when a potential is applied to the electrodes at a single applied potential.

Question 21

Coulometry (principle)

Answer 21

Measurement of the quantity of electricity which is directly proportional to the chemical reaction at the electrode.

Question 22

The measurement of the quantity of electricity at a fixed potential between 2 electrodes in an electrochemical cell.

Answer 22

Coulometry

Question 23

Coulometry formula

Answer 23

Q = I x T

Question 24

A current flow of 1 ampere per second

Answer 24

Coulomb

Question 25

• 96,500 coulombs

Answer 25

Faraday

Question 26

A coulometric titrator

Answer 26

Chloridometer

Question 27

Chloridometer is used for *measuring chloride ion concentration* in biological fluids such as ___.

Answer 27

Urine, Sweat, CSF

Question 28

An **electric conductor** that is in contact with an *ionic conductor*.

Answer 28

Electrode

Question 29

An electrode wherein it acts as **electron donor** or **electrical acceptor**.

Answer 29

Passive (Inert) Electrode

Question 30

An electrode wherein it acts as **ion donor** or **electron acceptor**.

Answer 30

Active (Participating) Electrode

Question 31

Electron reaction

Answer 31

An electrochemical process in which **charge transfer** takes place at the interface *between* the **electrode & electrolyte**.

Question 32

2 electrodes used in electrochemistry:

Answer 32

Indicator electrode, reference electrode

Question 33

An electrode that: • is **sensitive** and responds to changes in temperature. • **interacts** with the analyte of interest. • **shows** the activity of an ion in a solution

Answer 33

Indicator electrode

Question 34

• most common indicator electrode • measures a *potential* across a membrane specific for a certain analyte.

Answer 34

Ion-selective electrode

Question 35

An electrode that: • is used as a *fix reference* for the **direct measurement of the potential** between the *electrode and solution*. • has a constant potential and voltage source

Answer 35

Reference electrode

Question 36

3 reference electrodes

Answer 36

Standard Hydrogen electrode, Saturated calomel electrode, Silver / Silver chloride

Question 37

____ electrode allows *potentiometric* **measurement of a single type of ion** without interference of other ions.

Answer 37

Ion-selective electrode

Question 38

The ions that can be measured by Ion-selective electrode:

Answer 38

Sodium, Potassium Calcium, Lithium, Magnesium, Chloride

Question 39

Galvanic cell formula

Answer 39

E_cell = E_ISE – E_ref

Question 40

3 major types of ISE

Answer 40

1. Inert metal electrode / Ion selective glass ✓ SHE 2. Metal / Solid state electrode ✓ Ag–AgCl 3. Membrane electrode / Liquid Ion exchange membrane ✓ Ca²⁺ selective electrode

Question 41

• An electrode used as a *sensor* for _hydrogen_ or _sodium_ in biological solutions. • has **3 dimensional matrix** of varying oxides of elements

Answer 41

Glass Membrane

Question 42

• A **thin glass membrane** • has 3 layers that separate 2 solutions of different **hydrogen ion activity**

Answer 42

Hydrogen electrode

Question 43

A glass electrode **selectively permeable** only to **Na** (sodium)

Answer 43

Sodium glass electrode

Question 44

Basic types of MEMBRANES used in ISE

Answer 44

1. Solid ion exchange ✓ glass membrane ✓ solid state crystal membrane 2. Liquid ion exchange 3. Neutral carrier membrane

Question 45

A solid ion exchange membrane that is: • mechanically **strong** in thin sections • chemically **inert** • **non-porous** • highly **insoluble**

Answer 45

Solid state crystal membrane

Question 46

A membrane that consists of **water-immiscible solvents** which contain _ionizable species_ preferentially *soluble in the solvent phase*.

Answer 46

Liquid ion exchange

Question 47

ISE assay of Sodium (Na+) Sample: _____ Anticoagulant: _____ Hemolysis effect: _____

Answer 47

**Sample:** • serum, plasma, urine (24 hr), whole blood, sweat **Anticoagulant:** • Ammonium heparin, Lithium heparin, Lithium oxalate **Hemolysis effect:** • no significant change — due to decreased levels of intracellular sodium

Question 48

ISE assay of Potassium (K+) Sample: _____ Anticoagulant: _____ Hemolysis effect: _____

Answer 48

**Sample:** • serum, plasma, urine **Anticoagulant:** • N/A **Hemolysis effect:** • must be avoided

Question 49

This results in release of K+ from the rupture of cell counts, causing *spurious hyperkalemia*

Answer 49

**significantly elevated platelet counts** results in release of K+ from the rupture of these cell counts, causing ____.

Question 50

Describes the **electromotive force** _generated by H+_ at the glass tip

Answer 50

Nernst Equation