Notes – Properties of Water /Chemical Reactions. v v.

Notes – Properties of Water /Chemical

Reactions

Properties of Water

• Hydrogen Bonds – Weak forces between some covalently bonded molecules (polar molecules)

Properties of Water

• Properties of Water

• Cohesion – polar molecules attract and stick together

• Adhesion – water molecules stick to other molecules

• Examples

Surface tension, capillary action, high boiling point, water in sphere droplets, high heat capacity (storage)

Fig. 3-3

Water-conductingcells

Adhesion

Cohesion

150 µm

Directionof watermovement

Fig. 3-4

Properties of Water

• Properties of Water• Universal solvent –

More substances dissolve in water than any other molecule.

• Solvent – The substance other substances dissolve in.

• Solute – The substance being dissolved

Properties of Water

Solutions - Mixtures in which one or more substances are uniformly distributed in another.

• A Solute is dissolved in a solvent.

• Examples:

Aqueous solutions (water solvent), blood plasma, plant sap, seawater.

Salt in Water

• Salt in water dissolves and becomes positive and negative ions.

• Saltwater conducts electricity

• Salt in water dissolves and becomes positive and negative ions.

• Saltwater conducts electricity

Salt in Water

• Salt in water dissolves and lowers the freezing point of water.– Ex: Applying salt on icy

roads causes ice to melt

• Salt in water dissolves and raises the boiling point of water

Salt in Water

• Salt in water dissolves and lowers the freezing point of water.– Ex: Applying salt on icy

roads causes ice to melt

• Salt in water dissolves and raises the boiling point of water– Ex: Adding salt to water

makes water boil hotter and cooks food faster

Solubility – The maximum quantity of a substance that will dissolve in a certain

quantity of water at a specified temperature

• Solubility curve – Graphical representation of the amount of solute that dissolves in a given amount of solvent

Concentration – How much solute is dissolved in a specific quantity of solvent or

solutionSolubility can be

measured in :• per cent % - parts per

hundred• ppm – parts per

million• ppb – parts per billion

Solubility - concentrations depend on the amount/type of solvent and

the temperature• Saturated – solutions

holding the maximum amount of solute

• Unsaturated – solutions holding less than the max. amount

• Supersaturated – solutions holding more than the max amount of solute

Solubility - concentrations depend on the amount/type of solvent and the

temperature• Saturated – solutions

holding the maximum amount of solute

• Unsaturated – solutions holding less than the max. amount

• Supersaturated – solutions holding more than the max amount of solute

Solubility

Solubility

• Substances that dissolve in H2O are soluble.

• If substances do not dissolve in water they are insoluble.

• Substances that dissolve in water are ionic compounds or other polar molecules

Solubility

• Substances that dissolve in H2O are soluble.

• If substances do not dissolve in water they are insoluble.

• Substances that dissolve in water are ionic compounds or other polar molecules

• Ex: Salts, Alcohol

Solubility

• Nonpolar substances do not have partial charges.

• They do not readily dissolve in water

• Nonpolar substances include oils, petroleum products, kerosene

Solubility

• Nonpolar substances will dissolve in other nonpolar substances.

• Ex: Paint thinner for oil-based paints

• Like dissolves in like

• Soap breaks nonpolar molecules into smaller particles to make them more soluble in water

Measuring Solubility

Water Dissociation – Self Ionization

• Water can break down into ionized particles

H20 (l) = H+ (aq) + OH- (aq)

H20 + H+ = H30 +

Hydronium ion

ACID / BASE

• Acid/Base – Special compounds containing excess :

• Hydrogen (H+) (H30+ ) (hydronium) (acids)

or • Hydroxide (OH-) ions

(charged particles) dissolved in water (base)

ACID / BASE


• Hydrogen (H+) (H30+ ) (hydronium) (acids)or

• Hydroxide (OH-) ions (charged particles) dissolved in water (base)

ACID / BASE




• pH = Scale to measure H+ concentration (-log)

• pH 1= 1/10=1/101 H+• pH 2 = 1/100=1/102

• pH 3 = 1/1000= 1/103

• pH 1 = highest H+

• pH 14= lowest H+

ACID / BASE





• pH 1= 1/10=1/101 H+

• pH 2 = 1/100=1/102

• pH 3 = 1/1000= 1/103



ACID / BASE


• Hydrogen (H+) (hydronium) (acids)or



• pH 1= 1/10=1/101 H+

• pH 2 = 1/100=1/102

• pH 3 = 1/1000= 1/103



Acids

• Made up of molecules including one or more hydrogen (H+) (H30+ ) atoms that can be easily released in water solutions

• Substances in common have a sour taste

• Ex: Lemons, vinegar

Acids

• Made up of molecules including one or more hydrogen (H+) (H30+ ) atoms that can be easily released in water solutions

• Substances in common have a sour taste

• Ex: Lemons, vinegar

• Acids contain (H+) ions and compounds are renamed as acids

• Example:• HCl = Hydrogen

Chloride

renamed:

Hydrochloric Acid

Acids

Formula name

HCl =

H2CO3 =

HC2H3O2 =

HNO3 =

H3PO4 =

H2SO4 =

Acid Name

HCl =

H2CO3 =

HC2H3O2 =

HNO3 =

H3PO4 =

H2SO4 =

Acids

Formula name

HCl = Hydrogen Chloride

H2CO3 = Hydrogen Carbonate

HC2H3O2 = Hydrogen Acetate

HNO3 = Hydrogen Nitrate

H3PO4 = Hydrogen Phosphate

H2SO4 = Hydrogen Sulfate

Acid Name

HCl = Hydrochloric Acid

H2CO3 = Carbonic Acid

HC2H3O2 = Acetic Acid

HNO3 = Nitric Acid

H3PO4 = Phosphoric Acid

H2SO4 = Sulfuric acid

Acid / Base• Acid (H+) (H30+ ) =

Hydronium ion• pH 1-6• 1 is strongest , 6 is

weakest

Bases

• Ionic substances that include (OH-) hydroxide ions or generate (OH-) ions in solution

• In common substances have a bitter taste and slippery feel

• Ex: soap, peppers

Bases




• Bases keep their original compound name

• Ca(OH)2 =

• Mg(OH)2 =

• KOH =

• NaOH =

Bases




• Bases keep their original compound name

• Ca(OH)2 = Calcium Hydroxide

• Mg(OH)2 = Magnesium

Hydroxide• KOH = Potassium Hydroxide

• NaOH = Sodium Hydroxide

• Base (OH-) = Hydroxide ion

• pH 8-14• 14 is strongest, 8 is

weakest

Acid / Base• Acid (H+) =

Hydronium ion• pH 1-6• 1 is strongest , 6 is

weakest

• Base (OH-) = Hydroxide ion

• pH 8-14• 14 is strongest, 8 is

weakest

Neutral pH

• pH 7

• H+ = (OH)- = neutral

H+ + (OH)- =HOH=H2O

Ex: Distilled water

pH indicators

Indicators – show pH with color changes. H+ or (OH)- concentrationsEx: Litmus paper, phenolphthalein

Acid / Base

• Neutralization Equation• Reactants Products

• HCl + NaOH = NaCl + H2O

• Acid Base Salt Water• pH1 pH14 pH7 pH7

• Buffer – Baking Soda (HCO3-) prevents pH change

Acid / Base

• Neutralization Equation• Reactants Products• 1M HCl + 1M NaOH =

1M NaCl + 1M H2O

• Acid + Base = Salt + Water• pH1 pH14 pH7 pH7

• Buffer – Baking Soda (HCO3-) prevents pH change

• Titration – adding known quantities of acids and/or bases together to determine M or pH quantities

Notes – Properties of Water /Chemical Reactions. v v.

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