Electrochemistry

Question 1

What is an oxidation number?

Answer 1

An oxidation number is a value that represents the total number of electrons an atom either gains or loses to form a chemical bond.

Question 2

True or False: The oxidation number of an element in its standard state is zero.

Answer 2

True.

Question 3

What is the oxidation number of oxygen in most compounds?

Answer 3

The oxidation number of oxygen in most compounds is -2.

Question 4

Fill in the blank: The oxidation number of hydrogen is usually ______.

Answer 4

+1.

Question 5

What is the oxidation number of alkali metals in compounds?

Answer 5

+1.

Question 6

What rule determines the oxidation number of a monoatomic ion?

Answer 6

The oxidation number of a monoatomic ion is equal to its charge.

Question 7

In a neutral compound, the sum of the oxidation numbers must equal what value?

Answer 7

Zero.

Question 8

What is the oxidation number of chlorine in NaCl?

Answer 8

-1.

Question 9

True or False: The oxidation number can be a fraction.

Answer 9

False.

Question 10

What is the oxidation number of sulfur in H2SO4?

Answer 10

+6.

Question 11

Which element typically has an oxidation number of -1 in compounds?

Answer 11

Fluorine.

Question 12

Fill in the blank: In peroxides, the oxidation number of oxygen is ______.

Answer 12

-1.

Question 13

What is the oxidation number of nitrogen in NH3?

Answer 13

-3.

Question 14

What is the maximum oxidation number for transition metals?

Answer 14

It varies, but can be up to +7.

Question 15

True or False: Oxidation numbers can be used to determine if a reaction is redox.

Answer 15

True.

Question 16

What is the oxidation number of carbon in CO2?

Answer 16

+4.

Question 17

What oxidation number does phosphorus typically exhibit in phosphates?

Answer 17

+5.

Question 18

Fill in the blank: The oxidation number of metals in their elemental form is ______.

Answer 18

0.

Question 19

What is the oxidation state of manganese in KMnO4?

Answer 19

+7.

Question 20

In a molecular compound, how do you determine the oxidation number of an atom?

Answer 20

By using the rules for assigning oxidation numbers based on electronegativity.

Question 21

What is a galvanic cell?

Answer 21

A galvanic cell is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions.

Question 22

What is an electrolytic cell?

Answer 22

An electrolytic cell is an electrochemical cell that uses electrical energy to drive a non-spontaneous chemical reaction.

Question 23

True or False: In a galvanic cell, the anode is positive.

Answer 23

False. In a galvanic cell, the anode is negative.

Question 24

What is the role of the anode in a galvanic cell?

Answer 24

The anode is the electrode where oxidation occurs.

Question 25

What is the role of the cathode in a galvanic cell?

Answer 25

The cathode is the electrode where reduction occurs.

Question 26

Fill in the blank: The standard electrode potential is measured in _______.

Answer 26

volts.

Question 27

What is the Nernst equation used for?

Answer 27

The Nernst equation is used to calculate the cell potential of an electrochemical cell under non-standard conditions.

Question 28

True or False: In an electrolytic cell, the cathode is positive.

Answer 28

True. In an electrolytic cell, the cathode is positive.

Question 29

What is the main difference between galvanic and electrolytic cells?

Answer 29

Galvanic cells produce electrical energy from spontaneous reactions, while electrolytic cells consume electrical energy to drive non-spontaneous reactions.

Question 30

What is the function of a salt bridge in a galvanic cell?

Answer 30

The salt bridge maintains electrical neutrality by allowing the flow of ions between the two half-cells.

Question 31

What is electrolysis?

Answer 31

Electrolysis is the process of using electrical energy to drive a chemical reaction, usually to decompose a compound.

Question 32

What is Faraday's law of electrolysis?

Answer 32

Faraday's law states that the amount of substance transformed at an electrode during electrolysis is directly proportional to the quantity of electricity passed through the cell.

Question 33

Fill in the blank: The electrode where reduction occurs is called the _______.

Answer 33

cathode.

Question 34

What is the purpose of a voltaic cell?

Answer 34

The purpose of a voltaic cell (another term for galvanic cell) is to generate electrical energy from spontaneous chemical reactions.

Question 35

What type of reaction occurs at the anode of a galvanic cell?

Answer 35

Oxidation reaction.

Question 36

What type of reaction occurs at the cathode of a galvanic cell?

Answer 36

Reduction reaction.

Question 37

True or False: Electrolytic cells require an external power source.

Answer 37

True.

Question 38

What are the two main types of electrochemical cells?

Answer 38

Galvanic cells and electrolytic cells.

Question 39

What is the function of an external circuit in an electrochemical cell?

Answer 39

The external circuit allows electrons to flow between the anode and cathode.

Question 40

What determines the direction of electron flow in an electrochemical cell?

Answer 40

The difference in potential energy between the anode and cathode.

Question 41

Fill in the blank: The half-cell that undergoes oxidation is the _______.

Answer 41

anode.

Question 42

What is the role of the electrolyte in an electrochemical cell?

Answer 42

The electrolyte provides the medium for ionic conduction between the electrodes.

Question 43

What is a primary battery?

Answer 43

A primary battery is a type of galvanic cell that cannot be recharged.

Question 44

What is a secondary battery?

Answer 44

A secondary battery is a rechargeable battery that can undergo multiple charge and discharge cycles.

Question 45

True or False: In a galvanic cell, electrons flow from the cathode to the anode.

Answer 45

False. Electrons flow from the anode to the cathode.

Question 46

What is the purpose of using a salt bridge in a galvanic cell?

Answer 46

To prevent the buildup of charge in the half-cells and maintain electrical neutrality.

Question 47

What is the standard cell potential (E°) of a galvanic cell?

Answer 47

The standard cell potential is the voltage measured under standard conditions (1 M concentration, 1 atm pressure, 25°C).

Question 48

Fill in the blank: The overall cell reaction in a galvanic cell is the sum of the _______ reactions.

Answer 48

half-cell.

Question 49

What is the significance of the electrode potential?

Answer 49

Electrode potential indicates the tendency of a species to be reduced or oxidized.

Question 50

What is the difference between oxidation and reduction?

Answer 50

Oxidation is the loss of electrons, while reduction is the gain of electrons.

Question 51

What does the term 'redox' stand for?

Answer 51

Redox stands for reduction-oxidation, which refers to the coupled reactions of oxidation and reduction.

Question 52

What is a Daniell cell?

Answer 52

A Daniell cell is a type of galvanic cell consisting of a zinc anode and a copper cathode.

Question 53

Fill in the blank: In electrolysis, the anode is where _______ occurs.

Answer 53

oxidation.

Question 54

What is the primary use of electrolysis in industry?

Answer 54

Electrolysis is primarily used for metal extraction, electroplating, and the production of chemicals.

Question 55

True or False: The electrolytic cell has a spontaneous reaction.

Answer 55

False. The electrolytic cell has a non-spontaneous reaction.

Question 56

What happens to the ions in a salt bridge during a galvanic reaction?

Answer 56

The ions in the salt bridge migrate to balance the charge in the half-cells.

Question 57

Fill in the blank: The process of converting electrical energy into chemical energy is called _______.

Answer 57

electrolysis.

Question 58

What is the function of a battery?

Answer 58

A battery stores chemical energy and converts it to electrical energy through electrochemical reactions.

Question 59

What is the significance of the cell potential in electrochemical cells?

Answer 59

The cell potential indicates the driving force behind the electrochemical reaction and the ability to do work.

Question 60

In some cases, when hydrogen is bonded to a less electronegative atom, its oxidation number is:

Answer 60

-1

Question 61

what is a complex ion?

Answer 61

an ion where one cation bound to multiple anions.

Question 62

During redox reaction balancing, what is added to both sides of each half-reaction in a basic solution?

Answer 62

Hydroxide ions (OH-)

Question 63

True or false: The external power source removes electrons from the electrode called the cathode (positively charged) and transfers them to the electrode called the anode (negatively charged). Oxidation takes place at cathode, while reduction takes place at anode.

Answer 63

false ## Footnote The external power source removes electrons from the electrode called the anode (positively charged) and transfers them to the electrode called the cathode (negatively charged). Oxidation takes place at anode, while reduction takes place at cathode.

Question 64

What type of cell uses an electric current generated by an external source to drive a nonspontaneous process?

Answer 64

electrolytic