What is oxidation in a chemical reaction?
Oxidation is the loss of an electron by a reactant.
What is reduction in a chemical reaction?
Reduction is the gain of an electron by a reactant.
What is a redox reaction?
A redox reaction is any chemical reaction that transfers electrons from one atom to another.
What is an oxidizing agent?
An oxidizing agent is the reactant that gains one or more electrons (is reduced).
What is a reducing agent?
A reducing agent is the reactant that gives up one or more electrons (is oxidized).
In ionic compounds forming in a reaction, which direction do electrons move?
Electrons are transferred completely from the metal to the nonmetal.
In reactions that form ionic compounds, which species is always the reducing agent and which the oxidizing agent?
How are oxidizing and reducing agents identified in molecular (covalent) compounds?
Compare electronegativities; the more electronegative atom undergoes partial gain (oxidizing agent) and the less electronegative undergoes partial loss (reducing agent).
Using oxygen and hydrogen as an example, which is the oxidizing agent?
Oxygen is more electronegative than hydrogen, so oxygen is the oxidizing agent.
What does a positive or negative oxidation number indicate?
What must be true about total electrons lost and gained in a redox reaction?
The total number of electrons gained in reduction must equal the total number of electrons lost in oxidation.
What reaction types are given as examples of redox reactions?
Which reaction types are given as examples of non-redox reactions?
What is a half-reaction?
A half-reaction represents only the oxidation or only the reduction component of a redox reaction.
Where does oxidation occur and where does reduction occur in terms of electrodes?
What is a single-replacement reaction in the context of redox?
A single-replacement reaction is one atom replacing another in the reactants and is an example of a redox reaction.
How does the activity series relate to single-replacement reactions?
Any metal above another in the activity series is more reactive and more readily oxidized and will replace a less-reactive metal.
How were the terms oxidized and reduced originally defined historically?
Originally, oxidized meant gaining an oxygen atom and reduced meant losing an oxygen atom.
What is a combination reaction and what is a decomposition reaction?
What is the purpose of the half-reaction method in balancing redox reactions?
To write and balance the oxidation and reduction half-reactions separately before combining them into a balanced redox equation.
When balancing redox reactions in acidic solution which species are assumed present to balance H and O?
When balancing redox reactions in basic solution which species are assumed present to balance H and O?
How is electric potential defined and what are its units?
Electric potential is electric potential energy divided by charge; units are volts (joules per coulomb).
What is an electrochemical process?
Any conversion between chemical potential energy and electrical energy.
What happens to potential energy when electrons transfer between atoms in a redox reaction?
The potential energy is converted into electrical energy.
What is an electrochemical cell?
Any device that converts chemical energy into electrical energy or vice versa; redox reactions occur in all electrochemical cells.
What is a voltaic cell?
An electrochemical cell that converts chemical energy into electrical energy.
What is a half-cell in a voltaic cell?
One part of a voltaic cell in which either oxidation or reduction takes place.
How are the two half-cells in a voltaic cell connected and why?
They are connected by a bridge that allows movement of ions between the two half-cells.
What does the reduction potential measure?
A half-reaction's tendency to occur as a reduction (gain electrons).
What does the oxidation potential measure?
A half-reaction's tendency to occur as an oxidation (loss of electrons).
Why do scientists use the standard reduction potential?
Because absolute potentials cannot be measured; the standard reduction potential is measured relative to a standard hydrogen electrode.
What are the conditions for the standard cell potential measurement?
Ion concentrations 1 M, temperature 25℃, and pressure 100 kPa.
What is an electrolytic cell and how does its cell potential compare to a voltaic cell?
An electrolytic cell causes chemical change via applied electrical energy; its cell potential is negative, while a voltaic cell's potential is positive.
What energy conversions occur in voltaic and electrolytic cells?
Voltaic cell: chemical → electrical. Electrolytic cell: electrical → chemical.
What is electrolysis?
A process by which electrical energy is used to bring about a chemical change.
What components make up an electrolytic cell?
In a voltaic cell which direction do electrons flow through the external circuit?
Electrons flow from the anode to the cathode through an external circuit.
What is another name for a voltaic cell?
Battery
What is a fuel cell?
A type of voltaic cell in which a fuel undergoes oxidation and electrical energy can be continuously obtained.
What is electroplating?
The deposition of a thin layer of metal on an object in an electrolytic cell.
What is a redox reaction?
A redox reaction is any chemical reaction that transfers electrons from one atom to another.
What is an oxidizing agent?
An oxidizing agent is the reactant that gains one or more electrons (is reduced).
What is a reducing agent?
A reducing agent is the reactant that gives up one or more electrons (is oxidized).
In ionic compounds forming in a reaction, which direction do electrons move?
Electrons are transferred completely from the metal to the nonmetal.
In reactions that form ionic compounds, which species is always the reducing agent and which the oxidizing agent?
How are oxidizing and reducing agents identified in molecular (covalent) compounds?
Compare electronegativities; the more electronegative atom undergoes partial gain (oxidizing agent) and the less electronegative undergoes partial loss (reducing agent).
Using oxygen and hydrogen as an example, which is the oxidizing agent?
Oxygen is more electronegative than hydrogen, so oxygen is the oxidizing agent.
What does a positive or negative oxidation number indicate?
What must be true about total electrons lost and gained in a redox reaction?
The total number of electrons gained in reduction must equal the total number of electrons lost in oxidation.
What reaction types are given as examples of redox reactions?
Which reaction types are given as examples of non-redox reactions?
What is a half-reaction?
A half-reaction represents only the oxidation or only the reduction component of a redox reaction.
Where does oxidation occur and where does reduction occur in terms of electrodes?
What is a single-replacement reaction in the context of redox?
A single-replacement reaction is one atom replacing another in the reactants and is an example of a redox reaction.
How does the activity series relate to single-replacement reactions?
Any metal above another in the activity series is more reactive and more readily oxidized and will replace a less-reactive metal.
How were the terms oxidized and reduced originally defined historically?
Originally, oxidized meant gaining an oxygen atom and reduced meant losing an oxygen atom.
What is a combination reaction and what is a decomposition reaction?
What is the purpose of the half-reaction method in balancing redox reactions?
To write and balance the oxidation and reduction half-reactions separately before combining them into a balanced redox equation.
When balancing redox reactions in acidic solution which species are assumed present to balance H and O?
When balancing redox reactions in basic solution which species are assumed present to balance H and O?
How is electric potential defined and what are its units?
Electric potential is electric potential energy divided by charge; units are volts (joules per coulomb).
What is an electrochemical process?
Any conversion between chemical potential energy and electrical energy.
What happens to potential energy when electrons transfer between atoms in a redox reaction?
The potential energy is converted into electrical energy.
What is an electrochemical cell?
Any device that converts chemical energy into electrical energy or vice versa; redox reactions occur in all electrochemical cells.
What is a voltaic cell?
An electrochemical cell that converts chemical energy into electrical energy.
What is a half-cell in a voltaic cell?
One part of a voltaic cell in which either oxidation or reduction takes place.
How are the two half-cells in a voltaic cell connected and why?
They are connected by a bridge that allows movement of ions between the two half-cells.
What does the reduction potential measure?
A half-reaction's tendency to occur as a reduction (gain electrons).
What does the oxidation potential measure?
A half-reaction's tendency to occur as an oxidation (loss of electrons).
Why do scientists use the standard reduction potential?
Because absolute potentials cannot be measured; the standard reduction potential is measured relative to a standard hydrogen electrode.
What are the conditions for the standard cell potential measurement?
Ion concentrations 1 M, temperature 25℃, and pressure 100 kPa.
What is an electrolytic cell and how does its cell potential compare to a voltaic cell?
An electrolytic cell causes chemical change via applied electrical energy; its cell potential is negative, while a voltaic cell's potential is positive.
What energy conversions occur in voltaic and electrolytic cells?
Voltaic cell: chemical → electrical. Electrolytic cell: electrical → chemical.
What is electrolysis?
A process by which electrical energy is used to bring about a chemical change.
What components make up an electrolytic cell?
In a voltaic cell which direction do electrons flow through the external circuit?
Electrons flow from the anode to the cathode through an external circuit.
What is a fuel cell?
A type of voltaic cell in which a fuel undergoes oxidation and electrical energy can be continuously obtained.
What is electroplating?
The deposition of a thin layer of metal on an object in an electrolytic cell.
Multiply halves to equalize electron transfer, then add and cancel species to get the net equation.
Use the half-reaction method for reactions in acidic or basic solutions (use \(\mathrm{H^{+}}\)/\(\mathrm{H_2O}\) or \(\mathrm{OH^{-}}\)/\(\mathrm{H_2O}\) respectively).
\(\(E_{cell}^\circ = E_{cathode}^\circ - E_{anode}^\circ\)\)
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