chap 12 key terms

Question 1

alkaline cell

Answer 1

Alkaline cell- A commercial electrochemical cell with an alkaline electrolyte that is a moist paste rather than a solution.

Question 2

alloy

Answer 2

Alloy- A substance formed when other materials (e.g. carbon, other metals) are mixed with a metal.

Question 3

anode

Answer 3

Anode- An electrode at which an oxidation reaction occurs.

Question 4

battery

Answer 4

Battery- a combination of cells connected in series.

Question 5

cathode

Answer 5

Cathode- An electrode at which a reduction reaction occurs.

Question 6

combustion

Answer 6

Combustion- A rapid reaction with oxygen accompanied by the release of large amounts of heat; also called burning.

Question 7

conjugate redox pair

Answer 7

Conjugate redox pair- An oxidising agent and its corresponding reduced form

Question 8

displace

Answer 8

Displace- The transfer of electrons from an element to a positive ion which results in the ion leaving the solution as an element, e.g. when zinc is placed in a solution of copper (II) ions the displacement reaction is: Cu2+(aq) + Zn(s)  Zn2+(aq) + Cu(s)

Question 9

dry cell

Answer 9

Dry cell- A commercial galvanic cell with an electrolyte that is a moist paste rather than a solution.

Question 10

electrochemical cell

Answer 10

Electrochemical cell- A device that converts chemical energy into electrical energy, or vice versa.

Question 11

electrode

Answer 11

Electrode- A solid conductor in a half-cell at which oxidation or reduction reactions occur.

Question 12

electrolyte

Answer 12

Electrolyte- A solution or molten substance that conducts electricity by means of the movement of ions, e.g. a solution of sodium chloride (table salt).

Question 13

external circuit

Answer 13

External circuit- The section of an electrochemical cell in which electrons move. This section of the circuit will include the wires attached to the electrodes.

Question 14

galvanic cells

Answer 14

Galvanic cells- A type of electrochemical cell also known as a voltaic cell; a device that converts chemical energy into electrical energy.

Question 15

galvanometer

Answer 15

Galvanometer- An instrument for detecting electric current.

Question 16

half-cell

Answer 16

Half-cell- Half an electrochemical cell, which contains oxidant and conjugate reductant. When two half-cells are combined, a galvanic cell is formed.

Question 17

metal displacement reaction

Answer 17

Metal displacement reaction- A reaction in which a metal causes the ions of another metal in solution to gain electrons and so precipitate out as the solid metal. The metal to be displaced must be less reactive (higher on the electrochemical series) than the metal that is added, e.g. Zn metal will displace Cu from a solution of Cu2+ ions.

Question 18

oxidant

Answer 18

Oxidant- A reactant that causes another reactant to lose electrons during a redox reaction. This reactant is, itself, reduced and gains electrons, e.g. in the reaction between magnesium and oxygen, the oxygen is the oxidising agent, as it causes magnesium to lose electrons and form Mg2+: 2Mg(s) + O2(g)  2MgO(s).

Question 19

oxidation

Answer 19

Oxidation- The process by which a chemical species such as a metal atom or a non-metal ion loses electrons. An oxidation half-equation will show the electrons as products (on the right hang side of the arrow)

Question 20

oxidised

Answer 20

Oxidised- The state of having lost electrons. When a substance is oxidised, the electrons are written on the right-hand side of the arrow.

Question 21

primary cell

Answer 21

Primary cell- A galvanic cell that is non-rechargeable because the products of the reaction migrate away from the electrodes.

Question 22

reactivity series of metals

Answer 22

Reactivity series of metals- A ranking of metals in increasing order of their reactivity (ability to be oxidised), with the half-equations written as reduction equations of the corresponding ion. Least reactive metals are at the top and most reactive metals are at the bottom.

Question 23

redox reaction

Answer 23

Redox reaction- A reaction in which electron transfer occurs from the reducing agent to the oxidising agent. In the redox reaction, both oxidation and reduction occur.

Question 24

reduced

Answer 24

Reduced- The state of having gained electrons. When a substance is reduced, the electrons are written on the LHS of the arrow (as reactants) in the half-equation.

Question 25

reducing agent

Answer 25

Reducing agent- A reactant that causes another reactant to gain electrons during the redox reaction. This reactant is oxidised and loses electrons; e.g. in the reaction between magnesium and oxygen, the magnesium is the reducing agent, as it causes oxygen to gain electrons and form O2- ions: 2Mg(s) + O2(g)  2MgO(s)

Question 26

reduction

Answer 26

Reduction- The process by which a chemical species gains electrons. A reduction half-equation will show the electrons on the reactant side (LHS) of the equation.

Question 27

salt bridge

Answer 27

Salt bridge- An electrical connection between the two half-cells in a galvanic cell; it is usually made from a material saturated in the electrolyte solution.

Question 28

secondary cell

Answer 28

Secondary cell- An accumulator or rechargeable cell. Recharging can occur because the products formed in the cell during discharge remain in contact with the electrodes in a convertible form.

Question 29

spontaneous redox reaction

Answer 29

a redox reaction that occurs naturally

Question 30

voltaic cell

Answer 30

Voltaic cell- A type of electrochemical cell that is also known as a galvanic cell; a device that converts chemical energy into electrical energy.