4s4 electrolysis( Part 1)

ELECTROCHEMISTRY Electrolyte Vs Non-electrolyte Conductor Vs electrolyteElectrolysisElectrolytic cell

30/06/2010

Learning outcomesAt the end of the lesson, you should able to:1. state the meaning of electrolyte.2. Differentiate between the conductor and

electrolyte.3. classify substances into electrolytes and non-

electrolytes.4. relate the presence of freely moving ions to

electrical conductivity.

Electrolyte in daily lifeWhy the athletes drink 100-plus drinks or other electrolyte drinks

after their vigorous training? What is the function of electrolyte to the body?

 • Sweating is the way in which the body maintains its core temperature at 37°C. This results in

the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and if unchecked will lead to dehydration and eventually circulatory collapse and heat stroke.

• Electrolytes, especially sodium and potassium, in a drink will reduce urine output, enable the fluid to empty quickly from the stomach, promote absorption from the intestine and encourage fluid retention.

ExperimentC. To Investigate the Electrical Conductivity of Compounds

Title: • To compare the properties of ionic and covalent

compounds

Problem statement: • Do electrical conductivity of ionic compounds and

covalent compounds differ in solid state and molten state?

Previous

Carbonelectrodes

Molten NaCl conducts electricity

NaCl solution

NaCl solution conducts electricity

Electrical conductivity

• Molten NaCl, • NaCl solution

• They can conduct electricity- due to the presence of free moving / mobile ions in the electrolytes

are electrolytes

+-

++

-

-

-

-+ +

+

_ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _

-_ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ __ _ _ _ _

_ _ _ _

electrolyteElectrolytes can conduct electricity• due to the presence of free moving ions in the electrolytes

Eg.: NaCl solution

Electrolyte Vs Non-electrolyteElectrolyte Non-electrolyte

A substance that can conduct electricity in molten state or aqueous solution,and can undergoes chemical changes

A substance that CANNOT conduct electricity in either molten state or aqueous solution,

Molten

• Melted in high temperature.• A metal in its liquid state.

Think……

• Electricity can passes through a Cu wire but there is NO chemical reaction taking place.

• Do you classify Cu wire as an electrolyte?

Answer: No. Copper wire is not an electrolyte. It is a conductor. Because copper wire is in solid state and it does not undergo chemical reaction.

Conductor Vs ElectrolyteConductor Electrolyte

A substance that can conduct electricity in solid or molten state,

but not undergoes chemical change.

A substance that can conduct electricity in molten state or aqueous solution,and can undergoes chemical changes

Conductor Electrolyte

Electrolyte ? Non-electrolyte ?

• HCl solution• NH3 solution• Glucose solution• Molten lead, Pb• AgCl solution• Tetrachloromethane, CCl4

• Zinc wire• Copper penny

Electrolyte

Non-electrolyteNon-electrolyte

Non-electrolyte

Non-electrolyte

Electrolyte

Conductor

Conductor

ExplanationSubstance Answer Reason

HCl solution Electrolyte HCl solution is an ionic compound that consists of free moving H+ ions and Cl- ions, and can conduct electricity in aqueous state.

NH3 solution in organic solvent

Non-electrolyte NH3 solution is a covalent compound that exist as molecules in organic solvent. Hence, it cannot conduct electricity.

(* NH3 solution in WATER – can conduct electricity, because it exists as free mobile ions in water.)

Glucose solution Non-electrolyte Glucose solution is a covalent compound that exist as. Hence, it cannot conduct electricity.

Molten lead, Pb Non-electrolyte Molten lead consists only lead, Pb atoms. No free moving ions in the substance. Hence, it cannot conduct electricity.

AgCl solution Electrolyte AgCl solution is an ionic compound that consists of free moving Ag+ ions and Cl- ions, and can conduct electricity in aqueous state.

Tetrachloromethane, CCl4

Non-electrolyte Tetrachloromethane, CCl4 is a covalent compound that exist as molecules. Hence, it cannot conduct electricity.

Zinc wire Conductor Zinc wire is in solid state and it does not undergo chemical reaction.

Copper penny Conductor Copper penny is in solid state and it does not undergo chemical reaction.

Conductor Electrolyte Non-electrolyte

conduct electricity solid stateMolten stateX chemical change.

conduct electricity molten stateAqueous solution

chemical change.

X conduct electricity (molten stateAqueous solution)

Ionic compoundsFree moving ions

Covalent compounds –MoleculesX - in organic solvent-in water

Electrolysis

• A process whereby a compound in molten or aqueous state are broken down into its constituent elements by passing electricity through an electrolyte.

Electrolytic cell

• Battery• Ammeter (A device used to measure current) / Light bulb• Wire• Switch• Electrodes (Carbon / metal)

- a conductor in the form of wire, rod or plate which carries electric current in and out of the electrolyte during electrolysis.

• Electrolyte

Cations & Anions

Anionis a Negative ion

or

= positive

Cations are pawsitive.

Cations are + ve.

Anode Cathode

An electrode that donate electrons.

An electrode that receive electrons.

An electrode that undergoes oxidation.

An electrode that undergoes reduction.C-A+

Cations Cathode(+ ve ions)

Anions Anode(- ve ions)

“An OX chases a Red CAT “(Anode-Oxidation) (Reduction-Cathode)

(both start with vowels)(both start with consonants).

or

FORM 5

Oxidation Vs Reduction:

• “ L E O goes G E R ”(lose electron-oxidation, gain electron-reduction)

“O I L R I G ”• (Oxidation is Losing e-, Reduction is Gaining e- )

“ ELMO”(Electron Loss Means Oxidation )

“LEO the lion. GER! “ or “ LEO says GER”(Losing Electrons Oxidation, Gaining Electrons Reduction)

FORM 5

Why can only conduct electricity in molten state? But not in solid state?

Solid Lead (II) bromideMolten Lead (II) bromide

* Please watch the video clip that I have posted in FB...

Why can only conduct electricity in molten state? But not in solid state?

• Lead (II) bromide, PbBr2 is an ionic compound.• It consists of +ve Pb2+ ions and –ve Br- ions.• In solid PbBr2,

these ions do not move freely but are held in fixed positions in lattice.

• When PbBr2 melts (When in molten state), the ions are free to move. Hence, it can conduct electricity in molten state .

Popular Q

Summary

Conductor ElectrolyteNon-electrolyteElectrolysisCationsAnionsCathodeAnode

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