electricity and chemistry

define electrolysis

breakdown of molten or aqueous ionic compound using electricity

ways to make ionic solids into electrolyte

heat until the ionic solid melts or dissolve the ionic solid in water

if the electrolyte is a molten ionic compound, what are the products?

anode product (+) non-metallic element

cathode product (-) metallic element

if the electrolyte is an aqueous solution containing ions

anode product, oxygen gas or halogen if it’s a concentrated aqueous solution of a halide

cathode product, hydrogen gas or metallic element below hydrogen in the reactivity series

describe the electrolysis of copper(II) sulfate

anode - impure copper cathode pure copper electrolyte - aqueous copper (II) sulfate

copper from the anode goes to electrolyte as positive ions Cu(s) → Cu2+ (aq) + 2e-

copper metal forms at cathode Cu2+(aq) + 2e- → Cu(s)

impurities either go into the solution as positive ions or fall off the anode and deposit at the bottom of the container

define electroplating

coating an object with a thin layer of a metal to improve its appearance or prevent corrosion

what forms at each electrode during the electrolysis of molten lead(II) bromide?

anode (+): Bromine

cathode (-): Lead

what forms at each electrode during the electrolysis of concentrated hydrochloric acid?

anode (+): Chlorine

cathode (-): hydrogen

what forms at each electrode during the electrolysis of concentrated sodium chloride solution?

anode (+): chlorine

cathode (-): hydrogen

what forms at each electrode during the electrolysis of dilute sulfuric acid?

anode: oxygen

cathode: hydrogen

what forms at each electrode during the electrolysis of molten zinc chloride

anode: chlorine

cathode: zinc

what forms at each electrode during the electrolysis of copper sulfate using inert electrodes?

anode: oxygen

cathode: copper

what forms at each electrode during the electrolysis of copper sulfate using copper electrodes?

anode: copper ions

cathode: copper

oxidation occurs at the …

anode

reduction occurs at the …

cathode

predict the products of electrolysis of concentrated potassium bromide solution

anode: bromine

cathode: hydrogen

predict the products of electrolysis of concentrated copper iodide solution

anode: iodine

cathode: copper

predict the products of electrolysis of dilute zinc chloride solution

anode: oxygen

cathode: zinc

what’s electroplating?

process where a metal is coated with a layer of another metal

applications of electroplating

increase resistance to corrosion

improve appearance

write half equations for the reactions that occur at the electrodes when aqueous NaCl is electrolyzed

cathode: 2H+ +2e- → H2

anode: 2Cl- → Cl2 + 2e-

write half equations for the reactions that occur at the electrodes when molten lead(II) bromide is electrolyzed

cathode: Pd2+ + 2e- → Pb

anode: 2Br- → Br2 + 2e-

why are copper and steel-cored aluminum used in cables

aluminum and copper are both good conductors of electricity. aluminum is commonly used in overhead wires and copper is used in electrical wiring

why are plastics and ceramics used as insulators

plastics and ceramics both do not conduct electricity. they are used as insulators as they prevent the flow of electricity