Solutions, Acids,

Bases & pH

Solute –substance whose particles are dissolved in a solution

ie. salt, sugarSolvent – the substance in

which the solute dissolvesie. water “universal

solvent”

Dispersion of Sugar in Water

Conductivity – ability to conduct electricity

Freezing point – decreases Boiling point – increases Heat of solution – energy is

absorbed or released during the formation of a solution Energy released = exothermic Energy absorbed = endothermic

Properties of Liquid Substances

Surface area – ↑ surface area = ↑ rate

Stirring – moves dissolved particles away from the solid

Temperature – ↑ temperature = ↑ rate

Factors Affecting Dissolving Rate

Factors Affecting Dissolving Rate

One of the most important aspects of a living system is the degree of acidity or alkalinity

Ionization of water -breaking apart water molecules into ions of opposite chargeHOH + HOH H3O+ +

OH-

(water) (water) (hydronium)

(hydroxide)

Acid – ionic compound that produces hydronium ions (H3O+) when dissolved in water

Stronger acid = more hydronium ions Number of hydronium ions in solution is greater than the number of hydroxide ions

AcidsAcidsAcidsAcidsCharacteristics of Acids

• Tastes sour• Reacts strongly with metals• Conducts electricity in water• Turns blue litmus paper red• Generally clear solutions• Proton donors (give H+)

Examples of AcidsVinegar H2SO4

Citrus fruits HNO3

Stomach acid (HCl)

Acetic acid CH3COOH Vinegar

Carbonic acid H2CO3 Carbonated beverages

Hydrochloric acid HCI Digestive juices in stomach

Nitric acid HNO3 Fertilizer production

Phosphoric acid H3PO4 Fertilizer production

Sulfuric acid H2SO4 Car batteries

Add Base to Water

OH-

OH-OH-

OH-

OH-OH-

OH-

OH-

Na+

Na+Na+

Na+Na+

Na+

Na+

Na+

NaOH Na+ + OH-

Base – ionic compound that produces hydroxide ions (OH-) when dissolved in water

Stronger base = more hydroxide ions Number of hydroxide ions in solution is greater than the number of hydronium ions

BasesBasesBasesBasesCharacteristics of Bases

• Tastes bitter• Reacts strongly with metals• Conducts electricity in water• Turns red litmus paper blue• Generally slippery feel• Proton acceptors (take H+)

Examples of BasesLye (NaOH) Ca(OH)2

Ammonia (NH3) KOH

Aluminum hydroxide Al(OH)3 Deodorant, antacid

Calcium hydroxide Ca(OH)2 Concrete, plaster

Magnesium hydroxide Mg(OH)2 Antacid, laxative

Sodium hydroxide NaOH Drain cleaner, soap production

NeutralizationNeutralizationReaction between an Acid & Base

that forms salt & water

HCl + NaOH HOH + NaCl(Hydrochloric Acid) + (Sodium Hydroxide) (Water) + (Salt)

Sodium chloride NaCl Food flavoring, preservative

Sodium carbonate Na2CO3 Used to make glass

Potassium chloride KCl Used as a salt substitute to reduce dietary intake of

sodiumPotassium iodide Kl Added to table salt to

prevent iodine deficiency

Magnesium chloride MgCl2 De-icer for roads

Calcium carbonate CaCO3 Chalk, marble floors, and tables

Ammonium nitrate NH4NO3 Fertilizer, cold packs

Remember!!During a chemical reaction:

Bonds are broken Elements are rearranged New compounds are formed

Balanced Equation - # of atoms of each element are equal on both sides of a chemical equation Reactants are shown on the left

Products are shown on the rightHCl + NaOH H2O + NaCl

Reactants Products

pH ScaleMeasure of hydronium (H3O+) ion

concentration pH affects the physical & chemical properties

of a substance

Acid – pH = 0-6

Neutral – pH = 7Neutral – pH = 7 Base – pH

= 8-14

A change of one pH unit changes the H+ concentration by a factor of 10.

A change of 1 pH unit changes the H3O+ concentration by a factor of 10

ie. pH 1 has ie. pH 1 has 10x more 10x more hydronium hydronium ions than pH ions than pH 2; 100x more 2; 100x more than pH 3, than pH 3, etc. etc.

Why do we need to know pH?

IndicatorChanges color as the pH changes

• Indicates the pH of the solution

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Works Cited