Redox Reactions and Electrochemistry

Flashcards about oxidation, reduction, and electrochemistry.

What was the original idea about the nature of an oxidation reaction?

The addition of an oxygen molecule to a substance.

What was the original idea about the nature of a reduction reaction?

The loss of oxygen from a molecule.

What are oxidation reduction reactions known as?

Reactions with a shift in electrons.

What does LEO the lion Says GER stand for?

Loss of Electrons Oxidation, Gain Reduction Electrons

What do ionic reactions involve?

Involves the complete gain or loss of an electron.

What type of change occurs in a covalent reaction?

Has a shift in the electrons and therefore contains a partial change.

What processes lead to an oxidation reaction?

Complete loss of electrons, shift of electrons away from an atom, gain of oxygen, loss of H by a covalent compound, increase in oxidation #.

What processes lead to a reduction reaction?

Complete gain of electrons, shift of electrons towards an atom, loss of oxygen, gain of H by a covalent compound, decrease in oxidation #.

What are oxidation numbers?

Positive and negative numbers that indicate the degree of oxidation or reduction an atom has obtained.

What value do uncombined elements have for oxidation number?

Zero

What oxidation number do monatomic ions have?

Equal to its ionic charge.

What oxidation number do Group 1 metals have?

+1

What oxidation number do Group 2 metals have?

+2

What oxidation number does F have?

-1, unless combined with a more electronegative substance.

What oxidation number does H have?

+1, unless combined with a metal then it is -1.

What oxidation number does O have?

Usually -2 except when combined with F then its +2.

What must the sum of all oxidation numbers in a compound equal?

Zero.

What must the sum of all polyatomic ions equal?

Their charge.

What are ways to identify a redox reaction?

Assign oxidation numbers and look for changes or look for uncombined element on one side is part of a compound on the other.

What are spectator ions?

These ions in the reaction do not change.

What happens to oxidizing agents?

Are being reduced.

What happens to reducing agents?

Are being oxidized.

What are half reactions?

Just one part of the reaction. It is the oxidation or reduction of the reaction and does not include spectator ions.

What happens in electrochemical cells?

The energy that is absorbed or released is converted to electrical energy.

What is the Zinc referred to as in a Zn in Cu +2 solution?

More active metal and is therefore oxidized.

What is an electrochemical cell?

A cell that converts between electrical energy and chemical energy.

What are the two types of electrochemical cells?

Voltaic and electrolytic.

What are voltaic cells?

These use spontaneous chemical reactions to run.

What is the anode?

The site of oxidation.

What is the cathode?

The site of reduction.

Where are electrons produced in Voltaic cells?

Zn bar because of the Oxidation half reaction. The Zn is the anode and is negatively charged.

How are extra ions transferred to each cell?

By the salt bridge to balance charge.

What are dry cells?

batteries

What are lead storage batteries?

car batteries

What are fuel cells?

These have renewable electrodes

What is electrolysis?

When electrical energy is used to bring about chemical change.

What are the two major differences between electrolytic and voltaic cells?

There is an external power source pushing the system and the electrodes have different charges.

In the production of NaOH from Brine or concentrated NaCl, what happens to the Cl- ions?

Cl- ions are oxidized into Cl2 gas at the anode and water is reduced into H2 gas at the cathode.

What are the main uses of electrolytic cells with metals?

electroplating, electrowinning and electrorefining, electropolishing, electromachining

What are the charges of the anode and cathode in Voltaic cell?

Anode is negative, cathode is positive

What are the charges of the anode and cathode in Electrolytic cell?

Anode is positive, cathode is negative