Topic 9 Oxidation and reduction Flashcards
(28 cards)
What is an anode?
Where oxidation takes place; in electrolysis, it is the + electrode and anions are attracted here.
What is a cathode?
Where reduction takes place; in electrolysis, it is the – electrode and cations are attracted here.
Define electrolysis.
Passage of electric current through an electrolyte.
What factors affect the amount of discharge in electrolysis?
- Current
- Charge on ion
- Duration of electrolysis
What is an electrolyte?
A substance that does not conduct electricity when solid, but does when molten or in aqueous solution and is chemically decomposed in the process.
What is an electrolytic cell?
Used to make non-spontaneous redox reactions occur by providing energy in the form of electricity from an external source.
What is electroplating?
A process of coating one metal with a thin layer of another metal, by electrolysis.
What is a half cell?
A metal in contact with an aqueous solution of its own ions.
What is the oxidation number of elements?
0.
What is the oxidation number of an ion?
Its charge.
What is the oxidation number of oxygen?
-2 (except in peroxides, -1).
What is the oxidation number of hydrogen?
+1 (except in metal hydrides, -1).
What is the oxidation number of fluorine?
-1.
Define oxidation.
The loss of e-, the gain of oxygen, the loss of hydrogen or the increase in oxidation number.
What is an oxidizing agent?
A substance that readily oxidizes other substances and is reduced in the process.
What does reactivity measure?
The readiness of a substance to gain or lose e-.
What is a redox reaction?
A reaction in which there is a transfer of e-, i.e. reduction and oxidation occurring simultaneously.
What is a reducing agent?
A substance that readily reduces other substances and is oxidized in the process.
Define reduction.
The gain of e-, the loss of oxygen, the gain of hydrogen or the decrease in oxidation number.
What is a salt bridge?
Allows the free movement of ions in a voltaic cell.
What is an example of a salt bridge?
Paper dipped in a saturated solution of KNO3.
What is shorthand notation used for?
For a voltaic cell.
What are standard conditions?
298 K, 1 atm, 1.0 M.
What is standard electrode potential?
The potential of one half cell compared against another half-cell, with the hydrogen half-cell arbitrarily given a value of 0 V.
