Solutions, Acids, & Bases III. Particles in Solution “Like Dissolves Like” Electrolytes

A. “Like Dissolves Like” Polar substances will only dissolve in polar liquids Rubbing alcohol and water Nonpolar substances will only dissolve in nonpolar liquids Oil and butter Substances that aren’t the same don’t mix. Oil and water

A. “Like Dissolves Like” NONPOLAR POLAR Detergents polar “head” with long nonpolar “tail” can dissolve both types (polar and nonpolar)

B. Electrolyte An electrolyte is a substance that when dissolved in water form ions Electrolytes get their name from the fact that the conduct electricity in water. Example: salt dissolved in water Many sports drinks contain “electrolytes” which are salts dissolved in water

B. Electrolytes - + - + - + Electrolyte Weak Electrolyte Non- salt - + acetic acid - + sugar Electrolyte Weak Electrolyte Non- Electrolyte solute exists as ions only Easily conducts electricity solute exists as ions and Molecules Slightly conducts electricity solute exists as molecules only Does NOT conduct electricity

B. Electrolytes Dissociation separation of +/- ions when an ionic compound dissolves in water

B. Electrolytes Ionization breaking apart of polar covalent molecules into ions when dissolving in water

Solutions, Acids, & Bases IV. Intro to Acids & Bases Definitions Properties Uses

HCl + H2O  H3O+ + Cl– A. Acids Acids contain at least one hydrogen atom that can be removed when the acid is dissolved in water. These form hydronium ions, H3O+. Also called a proton donor HCl + H2O  H3O+ + Cl–

A. Bases Bases form hydroxide ions (OH-) in a water solution. a proton acceptor NH3 + H2O  NH4+ + OH-

A. Indicators Indicators are an organic substance that changes color in an acid or base. Examples: litmus - red/blue phenolphthalein - colorless/pink goldenrod - yellow/red red cabbage juice - pink/green

B. Properties ACIDS BASES bitter taste sour taste pH greater than 7 corrosive electrolytes turn litmus blue slippery feel sour taste pH less than 7 corrosive electrolytes turn litmus red react with metals to form hydrogen (H2) gas

C. Uses ACIDS H3PO4 –phosphoric acid - soft drinks, fertilizer, detergents H2SO4 – sulfuric acid - fertilizer, car batteries HCl – hydrochloric acid - gastric (stomach) juice HC2H3O2 – acetic acid - vinegar

C. Uses BASES NaOH – sodium hydroxide -lye, drain and oven cleaner Mg(OH)2 – magnesium hydroxide - laxative, antacid NH3 –ammonia - cleaners, fertilizer

Solutions, Acids, & Bases V. Strength of Acids & Bases Strength vs. Concentration Strong vs. Weak pH

A. Strength vs. Concentration Strong and weak – tells how easy the acid or base dissociates in solution. Concentration – The amount of acid or base in a solution. It is possible to have a dilute concentration of a strong acid that would be less harmful than a concentrated weak acid.

A. Strength of Acids & Bases The strength of an acid or base depends on how completely a compound separates into ions when dissolved in water. Ions can carry an electric charge so a strong acid will carry more electricity than weak acid.

B. Strong vs. Weak Strong Acid/Base 100% ions in water strong electrolyte HCl, HNO3, NaOH, LiOH - + Weak Acid/Base few ions in water weak electrolyte HC2H3O2, NH3 - +

B. Strong Acids Acids that ionize almost completely in a solution are strong acids. Ex: HCl, HNO3, and H2SO4 They have a very low pH (0-1).

B. Strong Bases Bases that dissociate completely in a solution are strong bases. Ex: NaOH They have a very high pH (13-14)

C. pH Scale a measure of the concentration of H+ ions in a solution pH (potential of Hydrogen) a measure of the concentration of H+ ions in a solution measured with a pH meter or an indicator with a wide color range (0-14) 7 INCREASING ACIDITY NEUTRAL BASICITY 14

pH of Common Substances C. pH Scale pH of Common Substances

ConcepTest Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? A B

ConcepTest Is the following statement TRUE or FALSE? A strong acid has a lower pH than a weak acid. True- But: Strong/weak refers to amount of ionization whereas pH refers to concentration of H+.

Solutions, Acids, & Bases VI. Neutralization Neutralization Reaction

A. Neutralization Reaction Chemical reaction between an acid and a base. Products are a salt (ionic compound) and water.

A. Neutralization Reaction ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H2O = Neutralization does not always mean pH = 7.

A. Neutralization Reaction KOH + HNO3  H2O + KNO3 Acid Base Salt HNO3 KOH KNO3