Acids and Bases Acids: often have a tart or sour taste - Examples include citrus fruits, vinegar, carbonated beverages, car batteries Properties of Acids: 1. sour/tart taste 2. Aqueous solutions are electrolytes (conduct electricity) 3. Cause indicators to change color 4. Many metals react with acids to produce hydrogen gas 5. React with hydroxides (bases) to produce water and a salt (ionic compound)

Properties of Bases: 1. React with acids to form water and a salt 2. Taste bitter 3. Feel slippery 4. Bases will change colors of indicators 5. Aqueous solutions conduct electricity 6.Strong bases are extremely caustic to the skin and can cause deep, painful slow healing wounds Examples of common bases are antacid tablets, household cleaning supplies (soap, detergent, ammonia, windex,...)

Names and Formulas of Acids and Bases Acid: compound that produces hydrogen ions in water. - The general formula of an acid is HX where X is a monatomic or polyatomic anion. - You must know the formulas and names of the following acids HCl – hydrochloric acid HNO 3 – nitric acid H 3 PO 4 – phosphoric acid H 2 SO 4 – sulfuric acid

Bases: a compound that produces hydroxide ions (OH-) when dissolved in water. They are named as you would name ionic compounds. - Examples you must know NaOH – sodium hydroxide Ca(OH) 2 – calcium hydroxide KOH – potassium hydroxide When acids and bases react the products will be water and a salt. HCl + NaOH → NaCl + H 2 O

Water can act like an acid or a base: Water can self ionize or break up to form positive and negative ions. H 2 O → H + + OH - Waterhydrogen ion Hydroxide ion 2 H 2 O → H 3 O + + OH - Water Hydronium ion Hydroxide ion Hydrogen ions are also called protons. The term hydrogen ion and hydronium ion are used interchangeably.

How pH is calculated pH: a measure of the concentration of hydrogen ions in a solution. In pure water, there are an equal number of hydrogen and hydroxide ions because each water molecule breaks into one hydrogen ion and one hydroxide ion - [H + ] = [OH - ] in pure water - In any solution [H + ] x [OH - ] = 1.0 x pH = -log [H + ] - pOH = -log [OH - ] - pH + pOH = 14 (for all solutions) - pH is measured on a 0 to 14 scale. 0 being very acidic and 14 being very basic - Neutral = 7 - Acidic: 0 < pH < 7 Basic: 7< pH < 14 - See page 602 in your book

Measuring pH - Measuring pH is use for many applications (swimming pools, soil acidity for plant growth, medical diagnosis, ect.) Indicators: a substance that changes color in the presence of an acid or a base because its acid form is a different color than this base form. - The color is compared to a reference chart for that indicator in order to determine the pH of the solution. - For precise and continuous measurements of pH a pH meter is used pH meters: uses an electrode in which the voltage of the electrode changes with the hydrogen ion concentration of the solution. - See page 590 in your book

Acid-Base Theories Arrhenius Acids: acids are hydrogen containing compounds that ionize to produce hydrogen ions when dissolved in water. Arrhenius Base: compounds that ionize to yield hydroxide ions when dissolved in water.

Monoprotic Acids: compounds that have one ionizable hydrogen ions (HCl) Diprotic Acids: compounds that have two ionizable hydrogen ions (H 2 SO 4 ) Triprotic Acids: compounds that have three ionizable hydrogen ions (H 3 PO 4 ) Bronsted-Lowry Acids and Bases Bronsted-Lowry Acid: Hydrogen ion donor Bronsted-Lowry Base: hydrogen ion acceptor All Arrhenius acids and bases are also Bronsted-Lowry acids and bases, but not vice versa

Conjugate Acid: the particle formed when a base gains a hydrogen ion. Conjugate Base: the particle that remains when an acid has donated a hydrogen ion. Conjugate Acid-Base Pair: two substances related by the loss or gain of a single hydrogen ion. 2 HCl + Ca(OH) 2 → CaCl H 2 O AcidBaseConjugate Base Conjugate Acid Amphoteric: a substance that can act as an acid or a base. - Water is a amphoteric because it can act as an acid or a base depending on the type of reaction

Lewis Acids or Bases Lewis Acid: substance that can accept a pair of electrons to form a covalent bond. Lewis Base: substance that can donate a pair of electrons to form a covalent bond. - Table 20.6 page 598

Strengths of Acids and Bases For a list of Strong and Weak Acids and Bases see table 20.7 on page 600