SOLUTIONS,

ACIDS, AND

BASES

CHAPTER 8

8.1 FORMATION OF SOLUTIONS• Any State of matter can become

part of a solution.• For a solution to form, one

substance must dissolve in another.•Examples: •Example: gas dissolves in water, oxygen dissolves in blood, sugar dissolves in tea.

DISSOLVING• SOLUTE dissolves into the SOLVENT

Example: Salt is the solute, water is the solventWater is always a SolventSubstances can dissolve in water in 3 ways:DissociationDispersionIonization

DISSOLVING BY DISSOCIATION OF IONIC COMPOUNDS• The solute and solvent particles

attract one another.•Example: Saltwater: Water (polar molecule) is attracted to the sodium and chlorine ions and pulls the crystal apart.

•This is a physical change

DISSOLVING BY DISPERSION OF MOLECULAR COMPOUNDS

• Breaking into small pieces that spread throughout the solvent.•Example: Sugar water: Both sugar and water are polar molecules, so they attract one another. Because water molecules are always moving, they collide frequently with the sugar crystals. The surface sugar molecules break free of the crystal and is pulled into solution.

•This is a physical change

DISSOLVING BY IONIZATION OF MOLECULAR COMPOUNDS• Neutral molecules gain or

lose electrons•Example: When HCl gas dissolves in water, the hydrogen proton from the HCl molecule is transferred to a water molecule forming a hydronium ion H3O+, and a chloride ion, Cl -

• This is a chemical change.

PROPERTIES OF LIQUID SOLUTIONSPhysical Properties of a solution

differ from those of its solute and solvent

• Conductivity• Freezing Point and Boiling Point• Heat• During the formation of a solution,

energy is either released or absorbed.

FACTORS AFFECTING RATES OF DISSOLVINGDepends on the frequency and energy of

collisions that occur between particles of the reactants.

• Surface area• Increases possible collisions between solute and solvent

• Stirring• Increases likelihood of collisions between solute and solvent

• Temperature• Increases movement of particles and increases the energy of the collisions.

8.2 SOLUBILITYMaximum amount of a solute that

dissolves in a given amount of solvent at a constant temperature.

Expressed in grams of solute per 100 grams of solvent at a specified temperature.Solubility in 100g of Water at 20°C

Compound Solubility (g)Table Salt (NaCl) 36.0Baking Soda (NaHCO3) 9.6Table Sugar (C12H22O11) 203.9

Solutions are described as sutured, unsaturated, or supersaturated, depending on the amount of solute in solution.

Saturated Solutions – contains as much solute as the solvent can hold at a given temperature. Addition of more solute will not go into solution.

Unsaturated Solution – has less than the maximum amount of solute that can be dissolved. Addition of more solute will dissolve into solution.

Supersaturated Solutions – contains MORE solute than it can normally hold at a given temperature. Very unstable as extra solute can rapidly deposit our of solution.

FACTORS AFFECTING SOLUBILITYSolubility varies with the solvent used and the

conditions of the solution process.• Polarity of the Solvent – like dissolves like • Example: oil will not dissolve in water, but will

dissolve using nonpolar soap.• Temperature – the solubility of solids increases

as the solvent temperature increases. Gases usually become less soluble as the temperature of the solvent increases.• Example: adding sugar to warm tea instead of cold

tea. Carbon dioxide escapes from warm soda faster than cold soda.

• Pressure - Increasing the pressure on a gas increases its solubility in a liquid.• Example: pressurized Carbon dioxide in a sealed

bottle of soda is released when the bottle is opened (pchhhhh)

CONCENTRATION OF SOLUTIONSThe amount of solute dissolved in a

specified amount of solution.

Percent by Volume = Volume of solute x 100%

Volume of solution

Percent by Mass = Mass of solute x 100%

Mass of solution

8.3 PROPERTIES OF ACIDS AND BASESAcid is a compound that produces hydronium

ions (H3O+) when dissolved in water.• Proton Donors• Properties: Sour taste, Reactivity with metals ,

Color Changes in Indicators (litmus paper)Base is a compound that produces hydroxide

ions (OH-) when dissolved in water.• Proton Acceptors• Properties: Bitter Taste, Slippery Feel

Color Changes in Indicators (litmus paper, phenophthalein)

NEUTRALIZATION AND SALTSNeutralization is the reaction between an

acid and a base. The negative ions in an acid combine with the positive ions in a base to produce an ionic compound called a salt.

(H3O + Cl-) + (Na+ + OH-) → (H2O) + (Na++ Cl-)

acid base water salt

8.4 STRENGTH OF ACIDS AND BASESpH Scale -

describe the concentration of hydronium ions in a solution

Acid/Base pH Hydronium

(H3O+) Ions

Acid 1 HighNeutral 7 equalBase 14 Low