Electrochemistry

Question 1

What is Electrochemistry?

Answer 1

It is a branch of physical chemistry that uses the measurement of electrical signals associated with chemical systems within and electrochemical cell.

Question 2

What type of chemistry measures the inter conversion of electrical and chemical phenomena?

Answer 2

Electrochemistry

Question 3

What is electrochemistry used for in clinical chemistry?

Answer 3

It is used to measure the concentrations of ions, drugs, hormones, metals, gases.

Question 4

List the three main categories of electrochemistry.

Answer 4

Potentionmetry
Coulometry
Amperometry

Question 5

What is an electrochemical cell?

Answer 5

An electrochemical cell is typically two electrodes that bridge between a chemical system and an electrical system

Question 6

What is the device through which chemical energy changes to electrical energy?

Answer 6

Electrochemical cell

Question 7

What does the electrochemical cell measure and what does it relate to?

Answer 7

It measures current or voltage and relates it to the concentration of a chemical species (like ions)

Question 8

What does the chemical reaction create in an electrochemical cell system?

Answer 8

It creates a constant current between the two electrodes

Question 9

What is the relationship between the amount of current and the amount of ions in the solution?

Answer 9

The amount of current is proportional to the amount of ions in the solution.

Question 10

What do electrons flow away Fromm s to what do they flow to? What processes occur during these movements?

Answer 10

Electrons (e-) flow away from the anode = oxidation

and flow towards (accepted by) the cathode = reduction

Question 11

Explain oxidation and reduction in terms of electron transfer

Answer 11

Oxidation refers to the loss of electrons while reduction is the gain of electrons.

Question 12

Explain the principle behind electrodes

Answer 12

A metal placed into a solution of its own ions will produce a voltage potential relative to the concentration (or activity) of ions in the solution.

Question 13

What are the two types of electrodes?

Answer 13

Indicator electrode

Reference electrode

Question 14

What electrode is sensitive and responds to changes in concentration or activity of an ion species in the solution in which it is immersed?

Answer 14

Indicator electrode

Question 15

What electrode has a constant ion concentration and potential created by this electrode? This electrode doesn’t change within the reaction so can be used as a reference to gauge how much the indicator electrode changes

Answer 15

A reference electrode

Question 16

What must an indicator electrode only react with?

Answer 16

An indicator electrode must react only with the analyte of interest when immersed in the analyte solution.

Question 17

What are the two conditions for and indicator electrode

Answer 17

• Must react only with the a analyte of interest

- Must be selective by responding to one specific ion

Question 18

What are the two types of indicator electrode seen?

Answer 18

Ion selective membrane electrode

Liquid/polymer membrane electrode

Question 19

What is the most common indicator electrode type used?

Answer 19

Ion selective membrane electrode

Question 20

What does the ion selective membrane electrode do?

Answer 20

It measures the voltage potentials across a selective membrane, diffuses into the solution causing a charge separation.

Question 21

How does the liquid/polymer membrane electrode work?

Answer 21

Measures K using a valinomycin ionophore to prevent interference from Na or H and increased permeability to K

Question 22

What is valinomycin?

Answer 22

It is an ion transporter, neutral carrier that binds K in the center of a ring of oxygen atoms.

Question 23

what are the conditions for a reference electrode?

Answer 23

• Must be self contained

- Must have stable, simple components and a constant potential

Question 24

What is the use of the constant potential in reference electrodes?

Answer 24

The constant potential is what we are comparing/referencing the indicator electrode potential to

Question 25

What are we comparing or referencing the indicator electrode’s potential to?

Answer 25

Constant potential of the reference electrode

Question 26

What are the two common reference electrodes?

Answer 26

Saturated calomel electrode | Silver-silver chloride electrode

Question 27

How does the saturated calomel electrode work?

Answer 27

In saturated calomel electrode, HgCl in a paste form is in contact with metallic Hg in an electrolyte solution of KCl to keep a constant concentration.

Question 28

How does the silver-silver chloride electrode work?

Answer 28

The Ag-AgCl electrode has a AgCl-coated silver wire immersed in a solution or constant chloride concentration.

Question 29

Define potentiometry.

Answer 29

It is the measurement of an electrical potential difference between two e,ectrodes immersed in a solution.

Question 30

What is the measure of electrical voltage difference between two electrodes?

Answer 30

Potentiometry

Question 31

It is defined as the use of electrodes to measures voltages from chemical reactions

Answer 31

Potentiometry

Question 32

How are the electrodes in potentiometry characterized?

Answer 32

- A half-cell reaction: either oxidation or reduction - A half-cell potential: quantitative measurement of the energy of a half-cell reaction relative to a reference electrode

Question 33

What does the pH meter in potentiometry use to detect Hydrogen ions?

Answer 33

A specifically designed pH sensitive thin glass membrane

Question 34

How does the pH meter looks at the concentration of hydrogen ions?

Answer 34

By measuring the potential/voltage difference between one half-cell and the other, that is the indicator electrode vs the reference electrode

Question 35

What is the SI unit of charge?

Answer 35

Coulomb

Question 36

Define coulomb

Answer 36

The amount of charge flowing

Question 37

What is the base unit of electric current?

Answer 37

Ampere

Question 38

Define ampere

Answer 38

The rate of flow of charge. That is how fast charge is moving over time (s)

Question 39

What is 1 ampere in relation to a coulomb?

Answer 39

1 ampere is the flow of 1 coulomb of a charge per second. 1coulomb/1second

Question 40

How is electrical current calculated?

Answer 40

Charge/time

Question 41

What does coulometry measure?

Answer 41

Coulometry measures the electrical charge passing passing between two electrodes in an electrochemical cell.

Question 42

What is the relation between the amount of charge and half cell reaction?

Answer 42

The amount of charge passing between two electrodes is directly proportional to the oxidation or reduction reaction at one of the electrodes

Question 43

What is the term used to define the amount of electricity (in coulombs) consumed or produced in an electrochemical reaction?

Answer 43

Coulometry

Question 44

How is the amount of electricity calculated? (In coulombs)

Answer 44

Current * time

Question 45

What is coulometry used for?

Answer 45

Measures Cl amount in body fluids using the sweat chloride test which generates silver ions from a silver wire at the anode in the reaction.