Chapter 12 - Oxidation and Reduction

What does oxidation mean?

Loss of electron(s) by an atom

What does reduction mean?

Gain of electron(s) by an atom

What common mnemonic can be used to remember oxidation and reduction?

LEO goes GER

What does an oxidizing agent promote?

Promotes oxidation of another molecule. In the process, they themselves are reduced

What does a reducing agent promote?

Promotes reduction of another molecule. In the process, they themselves are oxidized

Al → Al 3+, is this oxidation or reduction?

Oxidation

Fe 2+ → Fe+, is this oxidation or reduction?

Reduction

What is the oxidation number for atoms in their elemental state (e.g. O2, Br2)?

Zero

What is the oxidation number for atoms in monoatomic ions?

Their oxidation number will be equal to their charge

What is the oxidation number for fluorine?

-1

What is the typical oxidation number for Group 1 metals?

+1

What is the typical oxidation number for Group 2 metals?

+2

What is the typical oxidation number for oxygen?

-2

What is the oxidation number for oxygen when it is as a peroxide?

-1

What is the oxidation number of carbon in CO2?

+4

What is the oxidation number of nitrogen in NH3?

-3

What is the first step involved in balancing redox reactions?

Break the redox reaction into half reactions, one for the reduction portion and another for the oxidation portion

What two types of electrochemical cells are there?

Galvanic (voltaic) cells and electrolytic cells

Which type of electrochemical cell is spontaneous?

Galvanic (voltaic) cells

Which type of electrochemical cell is non-spontaneous?

Electrolytic

What type of energy input is used to power electrolytic cells?

Electrical energy

When a battery is providing energy to a device, is it acting as a galvanic or electrolytic cell?

Galvanic

When a battery is being recharged, is it acting as a galvanic or electrolytic cell?

Electrolytic

The electrode where oxidation occurs is called what?

Anode

The electrode where reduction occurs is called what?

Cathode

What direction do electrons flow in regards to the two electrodes, the anode and cathode?

Electrons always flow from anode to cathode

In a galvanic cell, what does the salt bridge allow for?

Allows for balancing of charges as the redox reaction proceeds. It will anions to flow to the anode and cations to flow to the cathode

In a galvanic cell, which electrode is considered positive?

Cathode

In a galvanic cell, which electrode is considered negative?

Anode

Why is the anode considered the negative electrode in a galvanic cell?

It attracts negatively charged ions from the salt bridge, due to the anode donating its electrons to the cathode

In a galvanic cell, which electrode will shrink in size?

The anode

Will the potential of galvanic cells be positive or negative?

Positive

In an electrolytic cell, which electrode is considered positive?

Anode

In an electrolytic cell, which electrode is considered negative?

Cathode

Is a salt bridge needed in an electrolytic cell?

No

What is used in place of a salt bridge in an electrolytic cell?

A porous barrier that allows for ion flow

Will the potential of electrolytic cells be positive or negative?

Negative

Do electrolytic cells require an external power source?

Yes, as it is a nonspontaneous redox reaction

In this electrochemical cell, Zn | Zn2+ || Cu2+ | Cu, which is considered the anode?

The Zn portion. Anode is always written on the left side and cathode on the right side

What does the double vertical lines in Zn | Zn2+ || Cu2+ | Cu represent?

The salt bridge

What does the single vertical line in Zn | Zn2+ || Cu2+ | C represent?

A phase change

What is the formula for calculating overall standard cell potential?

E cell = E reduction + E oxidation

Does standard cell potential depend on coefficients?

No. You do not multiple cell potential if you multiplied the half reaction

Ag+ + e- → Ag has a standard reduction of 0.80 V. If you were to reverse this reaction, what would happen to the reduction value?

It would become - 0.80 V

What is the formula for volts?

Volt = Joule / Coulomb

What is the formula for calculating amperes?

Ampere = Coulumb / second

What is the value of Faraday's constant?

96500 Coulombs/mol of e-

What is the formula for calculating free energy using cell potential?

∆G = -nFE

A spontaneous reaction will have a (positive/negative) cell potential and a (positive/negative) free energy

Positive cell potential and negative free energy

A non-spontaneous reaction will have a (positive/negative) cell potential and a (positive/negative) free energy

Negative cell potential and positive free energy