electric cellselectric cells

a simple electric cell consists of two different metal electrodes placed in an electrolyte

metals high up in the reactivity series give up electrons more readily; negative electrode in the cell

metals low down in the reactivity series will be the positive electrode in the cell

voltage of electric cell depends on the positions of the two metals in the reactivity series; the farther apart they are, the higher the voltage

use of electric cell: portable energy such as batteries

portable energy: batteries

a simple electric cella simple electric cell

electric cellselectric cellsa simple electric cella simple electric cell

voltmeter

- +

zinc metal (negative electrode)

copper metal (positive electrode)

NaCl(aq)

consists of pieces of Cu and Zn metals in a solution of NaCl

zinc being more reactive than Cu is the negative electrode; Cu metal is the positive electrode

electric cellselectric cellsa simple electric cella simple electric cell at the Zn electrode, Zn atoms give up electrons to form Zn2+

ions

Zn(s) Zn2+(aq) + 2e-

at the Cu electrode, Cu2+ ions take in electrons to give Cu atoms

Cu2+(aq) + 2e- Cu(s)

overall reaction

Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)

reactive metalsreactive metals

coppercopper

electrolyteelectrolyte

electroplatingelectroplating

moving ionsmoving ions

cathodecathode

electrolysiselectrolysis

gives gives electrons toelectrons to

are are produced atproduced at

batterybattery

formform

takes takes electrons fromelectrons from

is negative is negative electrode inelectrode in

anodeanode

negative ionsnegative ions

non-metalsnon-metals anionsanionsareare

are discharged are discharged atat

is positive is positive electrode inelectrode in

formformpositive ionspositive ions

metals or Hmetals or H22

cationscations

are are produced atproduced at

are are discharged atdischarged at

areare

aluminiumaluminium

is used to extract

is used to extract

an example an example isis

is used to refine

is used to refine

decomposesdecomposes

is used in

is used in

an an example isexample is Cr-platingCr-plating

carry the current incarry the current in

containscontains

ionic ionic compoundcompound

(molten/solution)(molten/solution)

isis