Water & Solution

7/29/2019 Water & Solution

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CHAPTER 5: WATER & SOLUTIONCHAPTER 5: WATER & SOLUTIONCHAPTER 5: WATER & SOLUTIONCHAPTER 5: WATER & SOLUTION

PhysicalPhysicalPhysicalPhysical Characteristics of WaterCharacteristics of WaterCharacteristics of WaterCharacteristics of Water

Water can exists assolid (ice)

liquid (water)

gas (steam)

Water is a colourless, odourless & tasteless liquid. Density water = 1g/cm3 at 40C Boils at 1000C Freezes at 00C Neutral to litmus paper Poor conductor of heat


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Melting point, freezing point, boiling point of water.Melting point, freezing point, boiling point of water.Melting point, freezing point, boiling point of water.Melting point, freezing point, boiling point of water.

PointPointPointPoint ExplanationExplanationExplanationExplanation ExampleExampleExampleExample

Melting point Temperature at which solidsolidsolidsolid

(ice) changes to become liquidliquidliquidliquid

(water).

Melting point of ice = 0 OC

Freezing point Temperature at which liquidliquidliquidliquid

(water) changes to become

solidsolidsolidsolid (ice) .

Freezing point of water = 0 OC

Boiling point Temperature at which liquidliquidliquidliquid

(water) changes to become gasgasgasgas

(steam) .

Boiling point of water = 100 OC


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Graph of cooling waterGraph of cooling waterGraph of cooling waterGraph of cooling water Graph of heatGraph of heatGraph of heatGraph of heating watering watering watering water

Effects on impurities on the physical characteristics of water.Effects on impurities on the physical characteristics of water.Effects on impurities on the physical characteristics of water.Effects on impurities on the physical characteristics of water.

Effects onEffects onEffects onEffects on Effects on property of pure waterEffects on property of pure waterEffects on property of pure waterEffects on property of pure water

Freezing &

melting points

Lower the freezing point & melting point of water (blow 00C)

Boiling point Boils at temperature of more than 1000C

Density Density increase (1.03g/cm3 = sea water)

Conduction of

electricity

Good conductor of electricity when dilute acid is added to it.

Composition of waterComposition of waterComposition of waterComposition of water

Water is a chemical compound which is made up of Hydrogen Oxygen

It is possible to separate water into hydrogen and oxygen through the process ofelectrolysis.

Electrolysis of WaterElectrolysis of WaterElectrolysis of WaterElectrolysis of Water

Electrolysis of water is the process of breaking down water into its elements bypassing an electric current through it.


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Gas bubbles are released at both carbon rods. During electrolysis of water: Terminal anodeanodeanodeanode (+ve) : collect oxygenoxygenoxygenoxygen gas Terminal cathodecathodecathodecathode (-ve) : colect hydrogenhydrogenhydrogenhydrogen gas

What are the confirmation testsconfirmation testsconfirmation testsconfirmation tests for hydrogen gas and oxygen gas?

oxygenoxygenoxygenoxygen gas the glowing splinter bursts into flamflamflamflameseseses. hydrogenhydrogenhydrogenhydrogen gas the burning splinter is extinguishedextinguishedextinguishedextinguished & a pop soundpop soundpop soundpop sound is heard.

Volume of hydrogenhydrogenhydrogenhydrogen gasgasgasgas is 2 times2 times2 times2 times the volume of oxygen gasoxygen gasoxygen gasoxygen gas.

WHY??

H

H

O+


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Evaporation of WaterEvaporation of WaterEvaporation of WaterEvaporation of Water

Evaporation is a process in which a liquid changes to a gasliquid changes to a gasliquid changes to a gasliquid changes to a gas at any tempany tempany tempany temperature belowerature belowerature belowerature belowthe liquids boiling pointboiling pointboiling pointboiling point (below 1000C).

For example, waterwaterwaterwater in the plate will dry updry updry updry up if it is left in open air for a few hours.This is because water evaporateswater evaporateswater evaporateswater evaporates to become vapourvapourvapourvapour which is invisible.

How quicklyquicklyquicklyquickly or slowly evaporationslowly evaporationslowly evaporationslowly evaporation takes place is known as the rate of evaporation.rate of evaporation.rate of evaporation.rate of evaporation. The rate of evaporationrate of evaporationrate of evaporationrate of evaporation is highhighhighhigh if evaporation takes place quicklyquicklyquicklyquickly. It is lowlowlowlow if

evaporation takes place slowly.slowly.slowly.slowly.

Applications of the evaporation of waterApplications of the evaporation of waterApplications of the evaporation of waterApplications of the evaporation of water

Drying hair Drying clothes Preservation of agricultural products Processing of food


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Comparison between boiling and evaporation of water.Comparison between boiling and evaporation of water.Comparison between boiling and evaporation of water.Comparison between boiling and evaporation of water.

Solvent, Solute and solutionSolvent, Solute and solutionSolvent, Solute and solutionSolvent, Solute and solution

Liquid that is

used todissolve a

substance

(solute)

Mixture that is

forms from a

solvent and a

solute

Substance that

dissolves in a

solvent


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Dilute solution, concentrated solution and saturation solutionDilute solution, concentrated solution and saturation solutionDilute solution, concentrated solution and saturation solutionDilute solution, concentrated solution and saturation solution

Undissolved solutes in a saturated solution can be dissolved completely by heatingheatingheatingheating oradding more solventadding more solventadding more solventadding more solvent to the solution.

Solution and suspensionSolution and suspensionSolution and suspensionSolution and suspension

Liquid mixtures can be classified into:

Solutions : mixtures containing dissolved substancesdissolved substancesdissolved substancesdissolved substances. Suspensions : mixtures containing insoluble substances.insoluble substances.insoluble substances.insoluble substances.

SolutionSolutionSolutionSolution AspectsAspectsAspectsAspects SuspensionSuspensionSuspensionSuspension

A solute dissolvedsolute dissolvedsolute dissolvedsolute dissolved in a solvent CompositionCompositionCompositionComposition InsolubleInsolubleInsolubleInsoluble, suspended particles in

a liquid or gas

TinyTinyTinyTiny and well dispersed Size of particlesSize of particlesSize of particlesSize of particles LargerLargerLargerLarger than those in a solution

Transparent and clearTransparent and clearTransparent and clearTransparent and clear, allows

light to pass through

Nature of solutionNature of solutionNature of solutionNature of solution Opaque and cloudyOpaque and cloudyOpaque and cloudyOpaque and cloudy, does not

allows much light to pass

through

No sedimentNo sedimentNo sedimentNo sediment seen When left to sandWhen left to sandWhen left to sandWhen left to sand Solid particles settle to thesettle to thesettle to thesettle to the

bottombottombottombottom or floatfloatfloatfloat at the surfaceNo residue leftNo residue leftNo residue leftNo residue left on the filter

paper

FiltrationFiltrationFiltrationFiltration Residue lResidue lResidue lResidue lefteftefteft on the filter paper

HomogenousHomogenousHomogenousHomogenous because its

properties are the same

throughout

Type of solutionType of solutionType of solutionType of solution NonNonNonNon----homogenoushomogenoushomogenoushomogenous (cloudy)

Salt solution, acids, alkalis ExamplesExamplesExamplesExamples Some medicines, calamine lotion

Dilute SolutionDilute SolutionDilute SolutionDilute SolutionConcentratedConcentratedConcentratedConcentrated

SolutionSolutionSolutionSolution

SaturatedSaturatedSaturatedSaturated

SolutionSolutionSolutionSolution

Contains littlittlittlittlelelele

solutesolutesolutesolute, can

still dissolvedissolvedissolvedissolve

more solutemore solutemore solutemore solute

Contains a lota lota lota lot

of soluteof soluteof soluteof solute, can

still dissolvedissolvedissolvedissolve


Contains the

max amountmax amountmax amountmax amount

of soluteof soluteof soluteof solute,

cannotcannotcannotcannotdissolve anydissolve anydissolve anydissolve any



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SolubilitySolubilitySolubilitySolubility

SolubilitySolubilitySolubilitySolubility refers to the maximum amountmaximum amountmaximum amountmaximum amount of a sosososolutelutelutelute in grams that will dissolve in agiven amount of solventsolventsolventsolvent (liquid).

The rate of dissolving a soluterate of dissolving a soluterate of dissolving a soluterate of dissolving a solute refers to how fasthow fasthow fasthow fast a substance can dissolve in a givengivengivengivenamountamountamountamount of solventof solventof solventof solvent at a particular temperature.particular temperature.particular temperature.particular temperature.

It refers to the time taken by the dissolving process, that is, from the time the soluteis added to solvent until it has completely dissolved.


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Organic SolventsOrganic SolventsOrganic SolventsOrganic Solvents

There are substance that cannot dissolve in water but can dissolve in other solvents.For example, iodine, paint, oil, ink, and chlorophyll cannot dissolve or dissolve very

little in water.

Organic solventsOrganic solventsOrganic solventsOrganic solvents are solvents containing carbonsolvents containing carbonsolvents containing carbonsolvents containing carbon. They are usually used to dissolveorganic subtances. Water is an inoorganic solventWater is an inoorganic solventWater is an inoorganic solventWater is an inoorganic solvent because it does not contain carbon.does not contain carbon.does not contain carbon.does not contain carbon. Applications of organic solvents in daily life:

Organic solventsOrganic solventsOrganic solventsOrganic solvents UseUseUseUse

Alcohol -preparation of antiseptics, i.e: iodine solution

-kill germs on cuts

Turpentine -Remove paint and grease

Butyl ester -preparation of perfumes

Ether -the extraction of fats and oils

Amyl acetate -preparation of cosmetic products, i.e:lipstics

Acetone -nail varnishes

Organic solvent are also used to remove stains:Type of stainType of stainType of stainType of stain Organic solvent which can be usedOrganic solvent which can be usedOrganic solvent which can be usedOrganic solvent which can be used

Paint Petrol, turpentine, kerosene

Oil, grease Petrol, kerosene, benzene

Tar Petrol, turpentine

Plastic Cloroform

Ink Acetone, AlcoholChlorophyll Alcohol

Lipstick, nail varnish Acetone, Amyl acetate, Ethyl acetate

Iodine Alcohol

Rubber Benzene

Acid and AlkaliAcid and AlkaliAcid and AlkaliAcid and Alkali

Most acids and alkalis, especially strong are corrosive and dangerous.

However, not all acids are harmful. Some of our food and drinks contain differenttypes of acids. Oranges and lime contain citric acid. Vinegar contains ethanoic acid

and soft drinks contain carbonic acid.

Acid and alkalis only show their propertiesonly show their propertiesonly show their propertiesonly show their properties in the prepreprepresence of watersence of watersence of watersence of water, that is whendissolved in water. For example, solid acidssolid acidssolid acidssolid acids and alkalis have no efectalkalis have no efectalkalis have no efectalkalis have no efect on pH or litmuspH or litmuspH or litmuspH or litmus

paper.paper.paper.paper.


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The common acidscommon acidscommon acidscommon acids that are used in the laboratorylaboratorylaboratorylaboratory are corrosive. They include: Hydrochloric acid Sulphuric acid Nitric acid

The comcomcomcommonmonmonmon alkalialkalialkalialkalissss that are used in the laboratorylaboratorylaboratorylaboratory which include: Sodium hydroxide Potassium hydroxide Calcium hydroxide Ammonium hydroxide

Comparing the properties of acids and alkalis:Comparing the properties of acids and alkalis:Comparing the properties of acids and alkalis:Comparing the properties of acids and alkalis:

DifferencesDifferencesDifferencesDifferences SimilaritiesSimilaritiesSimilaritiesSimilarities

TasteTasteTasteTaste WhenWhenWhenWhen

touchedtouchedtouchedtouched

TestedTestedTestedTested

withwithwithwith

litmuslitmuslitmuslitmus

paperpaperpaperpaper

ppppHHHH

valuevaluevaluevalue

ReactionReactionReactionReaction

withwithwithwith

metalsmetalsmetalsmetals

ReactionReactionReactionReaction

withwithwithwith

carbonatescarbonatescarbonatescarbonates

ReacionReacionReacionReacion

withwithwithwith

ammoniumammoniumammoniumammonium

saltssaltssaltssalts Acids and

alkalis are

corrosive

and should

be handles

with care.

AcidsAcidsAcidsAcids Sour Feel like

water

Change

blue

litmus

paper

red

pH

value

of 7

No

reaction

No

reaction

Give off

ammonia

gas

The pH range is from 1 to 14

The lowerlowerlowerlower the pHpHpHpH value of an acidacidacidacid, the stronger the acidstronger the acidstronger the acidstronger the acid. For example, an acid withpH 3 is stronger acid than one with pH 6.

The higherhigherhigherhigher the pHpHpHpH value of an alkalialkalialkalialkali, the stronger the alkalistronger the alkalistronger the alkalistronger the alkali. For example, an alkaliwith pH 13 is stronger alkali than one with pH 8.

Distilled waterDistilled waterDistilled waterDistilled water has a pH value of 7777 and is neutralneutralneutralneutral.


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The use of acids and alkaThe use of acids and alkaThe use of acids and alkaThe use of acids and alkalis in our daily lifelis in our daily lifelis in our daily lifelis in our daily lifeAcidAcidAcidAcid UseUseUseUse

Hydrochloric

acid

-to make antiseptic agents and liquid detergents

Citric acid -to produce fruit juices and health saltsFormic acid -to coagulate latex

Benzoic acid -as a preservative in sauces and drinks

Nitric acid -to manufacture fertilisers, dyes, explosives and insect repellents

Ascorbic acid -to produce vitamin C tablets

Sulphuric acid -as car batteries

-to make detergents and fertilisers

Tartaric acid -to make soft drink

Acetic acid -to preserve food

AlkaliAlkaliAlkaliAlkali UseUseUseUseSodium

hydroxide

-to make detergents and soaps

-to manufacture plastic and rayon

Potassium

hydroxide

-to make liquid soap

-To dye cloth

Calcium

hydroxide

-to make cement

Ammonia

solution

-to prevent coagulation of latex

-as cleaning agent and bleach

Magnesium

hydroxide

-to produce toothpaste

NeutralisationNeutralisationNeutralisationNeutralisation

Neutralisation is the process in which an acid reacts with an alkali to form a neutralneutralneutralneutralsolutionsolutionsolutionsolution containing saltsaltsaltsalt and water.water.water.water.

The word equation for the neutralisation reaction is:Acid + Alkali salt + water

Complete neutralization of an acid and alkali can be done by using a process calledtitrationtitrationtitrationtitration.

TitrationTitrationTitrationTitration is processprocessprocessprocess where an acid is gradually addedacid is gradually addedacid is gradually addedacid is gradually added from a burette to an alkalialkalialkalialkali untilthe end pointend pointend pointend point of neutralization is reachedneutralization is reachedneutralization is reachedneutralization is reached.

The end point is reached when an indicator that has been added to the alkali changescolour.

An indicatorindicatorindicatorindicator is a substancesubstancesubstancesubstance which changes colourchanges colourchanges colourchanges colour according to the pHaccording to the pHaccording to the pHaccording to the pH.


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Water purificationWater purificationWater purificationWater purification

Water from natural sources contains impurities. These impurities are dissolved gasses,microorganisms, decaying and dissolved substances, suspended particles and wastes.

Some microorganisms in water can causes diseases such as cholera. Therefore, water must bewater must bewater must bewater must be purifiedpurifiedpurifiedpurified before it can be used for drinking.Methods of water purificationMethods of water purificationMethods of water purificationMethods of water purification

(1)(1)(1)(1) FiltrationFiltrationFiltrationFiltration-removes the suspended solid particlesremoves the suspended solid particlesremoves the suspended solid particlesremoves the suspended solid particles such as clay and sand in the water.

-filtration process can be carried out by using sand particles as the filter:

this system uses layers of fine sand, coarse sand, small stones and pebbles.

the liquid that goes through the filter is called the filtrate and the solid

material left behind in the filter is called the residue.

-this method of purification does not remove microorganismsdoes not remove microorganismsdoes not remove microorganismsdoes not remove microorganisms and dissolveddissolveddissolveddissolved

substances.substances.substances.substances.-therefore, filtered water is unsafe for drinking.

(2)(2)(2)(2) BoilingBoilingBoilingBoiling-kill most of the microorganismskill most of the microorganismskill most of the microorganismskill most of the microorganisms in the water.

-Does not removenot removenot removenot remove suspended particlessuspended particlessuspended particlessuspended particles and dissolved substancesdissolved substancesdissolved substancesdissolved substances.

(3)(3)(3)(3) ChlorinationChlorinationChlorinationChlorination-also kills microorganismskills microorganismskills microorganismskills microorganisms in the water.

-used to treat large quantities of watertreat large quantities of watertreat large quantities of watertreat large quantities of water.

-Does not remove suspended parnot remove suspended parnot remove suspended parnot remove suspended particlesticlesticlesticles and dissolved substancesdissolved substancesdissolved substancesdissolved substances.-Usually used in water purification plants and swimming poolsswimming poolsswimming poolsswimming pools.

(4) DistillationDistillationDistillationDistillation

-produces pure waterproduces pure waterproduces pure waterproduces pure water (free from microorganisms, dissolve substances and

suspended particles)

-this method indicate 2 processes (boiling and cindicate 2 processes (boiling and cindicate 2 processes (boiling and cindicate 2 processes (boiling and condensation)ondensation)ondensation)ondensation)

-distilled water is use to prepare chemical solutions in laboratories and liquid

medicines in pharmacies.

-this method is quite expensiveexpensiveexpensiveexpensive and takes long time.takes long time.takes long time.takes long time.

Water Supply SystemWater Supply SystemWater Supply SystemWater Supply System

The main water in our country is rainwater and river water Before they are purified, rainwater and river water are collected in reservoir.


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Water treatment processWater treatment processWater treatment processWater treatment process

(A)(A)(A)(A)ReservoirReservoirReservoirReservoirWater is pumped from the river and keptkeptkeptkept in a reservoir for several daysseveral daysseveral daysseveral days.This is allowsallowsallowsallows the suspended mattersuspended mattersuspended mattersuspended matter in the water ( such as dead leaves) to settlesettlesettlesettle to

the bottombottombottombottom of the reservoir.

At the same time, the water is exposedexposedexposedexposed to sunlightsunlightsunlightsunlight which kills somekills somekills somekills some of themicroorganismsmicroorganismsmicroorganismsmicroorganisms in the water.

(B)(B)(B)(B) Screening tankScreening tankScreening tankScreening tankWater from the reservoir is channelled through a metal screen to remove bigremove bigremove bigremove big

obobobobjectsjectsjectsjects like leaves, fish, rubbish, etc.

(C)(C)(C)(C) Aeration tankAeration tankAeration tankAeration tankThe water then goes into an aeration tank where the water is aeratedwater is aeratedwater is aeratedwater is aerated by pumpingpumpingpumpingpumping

it intointointointo the airairairair so that oxygenoxygenoxygenoxygen from the air dissolve in the water.dissolve in the water.dissolve in the water.dissolve in the water.

This help to get ridget ridget ridget rid of the unpleasant smellunpleasant smellunpleasant smellunpleasant smell and the tatatatastestesteste from the water.(D)(D)(D)(D)Coagulation tankCoagulation tankCoagulation tankCoagulation tankWater is then pumped into the coagulation tank.Alum, lime and sometimes activated carbon are added and mixed into the water.LimeLimeLimeLime is added to reduce the acidityreduce the acidityreduce the acidityreduce the acidity of the water.Activated carbon absorb toxic gasesActivated carbon absorb toxic gasesActivated carbon absorb toxic gasesActivated carbon absorb toxic gases and rerereremoves unpleasant smellmoves unpleasant smellmoves unpleasant smellmoves unpleasant smell from thewater.AlumAlumAlumAlum coagulates fine, suspended particles in the watercoagulates fine, suspended particles in the watercoagulates fine, suspended particles in the watercoagulates fine, suspended particles in the water, causing them to clumpclumpclumpclump

(group) together(group) together(group) together(group) together to form bigger lumps.

(E)(E)(E)(E) Sedimentation tankSedimentation tankSedimentation tankSedimentation tankThe solid lumpssolid lumpssolid lumpssolid lumps sink to the bottomsink to the bottomsink to the bottomsink to the bottom of the tank and are eventually removedremovedremovedremoved

througthrougthrougthrough valves.h valves.h valves.h valves.


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(F)(F)(F)(F) Filtration tankFiltration tankFiltration tankFiltration tankThe water is filtered to remove any remaining suspended particlesremove any remaining suspended particlesremove any remaining suspended particlesremove any remaining suspended particles.This is done by passingpassingpassingpassing the water through several layers of sand and stonesseveral layers of sand and stonesseveral layers of sand and stonesseveral layers of sand and stones.

(G)(G)(G)(G)Chlorination & Fluoridation tankChlorination & Fluoridation tankChlorination & Fluoridation tankChlorination & Fluoridation tankChlorineChlorineChlorineChlorine is added to kill microorganismskill microorganismskill microorganismskill microorganisms in the water.FluorideFluorideFluorideFluoride salt is added to prevent tooth decay.prevent tooth decay.prevent tooth decay.prevent tooth decay.

(H)(H)(H)(H)StorageStorageStorageStorageThe clean treated water is then pumped into storage tanks.From the storage tank, the water is pumpedwater is pumpedwater is pumpedwater is pumped to service reservoirsservice reservoirsservice reservoirsservice reservoirs located on hills

or higher ground in housing areas.

From the service reservoirs, water flows downwardsflows downwardsflows downwardsflows downwards to the houses through pipes.houses through pipes.houses through pipes.houses through pipes.


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Water PollutionWater PollutionWater PollutionWater Pollution

Water pollutionWater pollutionWater pollutionWater pollution is the contaminationcontaminationcontaminationcontamination of waterwaterwaterwater bodies (e.g. lakes, rivers, oceans,groundwater).

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Water & Solution