Notes – Properties of Water /Chemical Reactions

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Properties of Water Hydrogen Bonds – Weak forces between some covalently bonded molecules (polar molecules)

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-conducting cells Adhesion Cohesion 150 µm Direction of water movement

Fig. 3-4

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

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 solution Solubility 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 - 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

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

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 H 2 0 ( l ) = H + ( aq ) + OH - ( aq ) H H + = H Hydronium ion

ACID / BASE Acid/Base – Special compounds containing excess : Hydrogen (H+) (H ) (hydronium) (acids) or Hydroxide (OH-) ions (charged particles) dissolved in water (base)

ACID / BASE Acid/Base – Special compounds containing excess : Hydrogen (H+) (H ) (hydronium) (acids)or Hydroxide (OH-) ions (charged particles) dissolved in water (base)

ACID / BASE Acid/Base – Special compounds containing excess : Hydrogen (H+) (H ) (hydronium) (acids)or Hydroxide (OH-) ions (charged particles) dissolved in water (base) pH = Scale to measure H+ concentration (-log) pH 1= 1/10=1/10 1 H+ pH 2 = 1/100=1/10 2 pH 3 = 1/1000= 1/10 3 pH 1 = highest H+ pH 14= lowest H+

ACID / BASE Acid/Base – Special compounds containing excess : Hydrogen (H+) (H ) (hydronium) (acids)or Hydroxide (OH-) ions (charged particles) dissolved in water (base) pH = Scale to measure H+ concentration (-log) pH 1= 1/10=1/10 1 H+ pH 2 = 1/100=1/10 2 pH 3 = 1/1000= 1/10 3 pH 1 = highest H+ pH 14= lowest H+

ACID / BASE Acid/Base – Special compounds containing excess : Hydrogen (H+) (hydronium) (acids)or Hydroxide (OH-) ions (charged particles) dissolved in water (base) pH = Scale to measure H+ concentration (-log) pH 1= 1/10=1/10 1 H+ pH 2 = 1/100=1/10 2 pH 3 = 1/1000= 1/10 3 pH 1 = highest H+ pH 14= lowest H+

Acids Made up of molecules including one or more hydrogen (H+) (H ) 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+) (H ) 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 = H 2 CO 3 = HC 2 H 3 O 2 = HNO 3 = H 3 PO 4 = H 2 SO 4 = Acid Name HCl = H 2 CO 3 = HC 2 H 3 O 2 = HNO 3 = H 3 PO 4 = H 2 SO 4 =

Acids Formula name HCl = Hydrogen Chloride H 2 CO 3 = Hydrogen Carbonate HC 2 H 3 O 2 = Hydrogen Acetate HNO 3 = Hydrogen Nitrate H 3 PO 4 = Hydrogen Phosphate H 2 SO 4 = Hydrogen Sulfate Acid Name HCl =Hydrochloric Acid H 2 CO 3 = Carbonic Acid HC 2 H 3 O 2 = Acetic Acid HNO 3 = Nitric Acid H 3 PO 4 = Phosphoric Acid H 2 SO 4 = Sulfuric acid

Acid / Base Acid (H+) (H ) = Hydronium ion pH 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 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 keep their original compound name Ca(OH) 2 = Mg(OH) 2 = KOH = NaOH =

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 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 is strongest, 8 is weakest

Acid / Base Acid (H+) = Hydronium ion pH is strongest, 6 is weakest Base (OH-) = Hydroxide ion pH is strongest, 8 is weakest

Neutral pH pH 7 H + = (OH) - = neutral H + + (OH) - =HOH=H 2 O Ex: Distilled water

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

Acid / Base Neutralization Equation ReactantsProducts HCl + NaOH = NaCl + H 2 O Acid Base Salt Water pH1 pH14 pH7 pH7 Buffer – Baking Soda (HCO 3 -) prevents pH change

Acid / Base Neutralization Equation ReactantsProducts 1M HCl + 1M NaOH = 1M NaCl + 1M H 2 O Acid + Base = Salt + Water pH1 pH14 pH7 pH7 Buffer – Baking Soda (HCO 3 -) prevents pH change Titration – adding known quantities of acids and/or bases together to determine M or pH quantities