Transcript CHAPTER 25
CHAPTER 25 0011 0010 1010 1101 0001 0100 1011 1 2 4 Acids, Bases and Salts Section 1-Acids and Bases 0011 0010 1010 1101 0001 0100 1011 • Acid—a substance that produces hydrogen ions in a water solution (H donor) • It is the ability to produce these ions that gives acid their characteristic properties • Properties: sour taste, corrosive, react strongly w/certain metals, turns litmus red 1 2 4 Common Acids 0011 0010 1010 1101 0001 0100 1011 • Citric acid—found in citrus fruits • Lactic acid—found in yogurt and buttermilk • Acetic acid—vinegar (pickles • Hydrochloric acid—in your stomach • Others used in industry: sulfuric, phosphoric, nitric and hydrochloric 1 2 4 Bases 0011 0010 1010 1101 0001 0100 1011 • Base—any substance that forms hydroxide ions, OH, in a water solution OR any substance that accepts H from acids (H acceptor) • Properties: many are crystalline solids, feel slippery, taste bitter, can be corrosive, turns litmus blue 1 2 4 0011 0010 1010 1101 0001 0100 1011 Common examples of Bases: 1 2 •Ex: egg whites, baking powder, milk of magnesia, antacids, ammonia, etc. •Chart-pg. 769 4 Solutions of Acids and Bases 0011 0010 1010 1101 0001 0100 1011 • Compounds that can form hydroxide ions in solution are bases 1 2 • These substances release OH ions in water. **If a solution contains MORE OH ions than H3O ions, it is referred to as BASIC 4 • Ammonia in solution—pg. 771 (harmful effects of ammonia w/other cleaners) 0011 0010 1010 1101 0001 0100 1011 • Solutions of both acids and bases produce some ions that are capable of carrying electric current to some extent• **These solutions are said to be CONDUCTORS 1 2 4 Section 2—Strength of Acids & Bases 0011 0010 1010 1101 0001 0100 1011 • The strength of an acid or base depends on how completely a compound separates into ions when dissolved in water • Strong acid—an acid that ionizes almost completely in solution – Ex: HCl, HNO3 and H2SO4 1 2 4 • Weak acid—an acid that only partly ionizes – Ex: acetic and carbonic acids Bases: 0011 0010 1010 1101 0001 0100 1011 • Strong base—dissociates completely in solution 1 2 – Ex: sodium hydroxide Weak base—one that does not ionize completely ex: Ammonia Remember: Strong and Weak acids and bases are not to be confused with DILUTION and CONCENTRATION of acids and bases 4 pH of a Solution 0011 0010 1010 1101 0001 0100 1011 • pH—a measure of the concentration of H ions in a solution • The greater the H concentration is, the lower the pH is and the more acidic the solution • pH—measures how acidic or 1 2 4 pH Scale 0011 0010 1010 1101 0001 0100 1011 • • • • • pH scale—ranges from 0 to 14 0-most acidic 14-most basic 7-neutral Universal indicator paper—can be sued to determine pH of substances (colors are matched to determine pH level) 1 2 4 0011 0010 1010 1101 0001 0100 1011 • pH meter-can be used to determine the pH of a solution more precisely • Operated by immersing electrodes in the solution and reading a dial • Blood pH—pH of blood must remain between 7.0 and 7.8 • Buffers—help keep your blood close to a nearly constant pH of 7.4 (neutralizers) 1 2 4 Section 3: Salts 0011 0010 1010 1101 0001 0100 1011 • Neutralization: a chemical reaction between an acid and a base that takes place in a water solution • Salt: a compound formed when the negative ions from an acid combine w/the positive ions from a base • Acid + Base- Salt + Water 1 2 4 Salts 0011 0010 1010 1101 0001 0100 1011 • Are essential for many animals large and small • Most are composed of a positive metal ion and an ion with a negative charge • Salts also form when acids react with metals (a single displacement reaction) • Visualizing Salt—pg. 779 1 2 4 Titration 0011 0010 1010 1101 0001 0100 1011 • Titration: a process in which a solution of known concentration is used to determine the concentration of another solution • Ex: using phenolphthalein to determine concentration of acid/base solution—pg 780 • Natural indicators: red cabbage, radishes, roses, hydrangeas, grape juice, etc. 1 2 4 Soaps and Detergents 0011 0010 1010 1101 0001 0100 1011 • Soap: organic salts with a nonpolar organic chain of carbon atoms on one end, and either a sodium or potassium salt of a carboxylic acid at the other end – Ex: pg. 782 1 2 4 Detergents 0011 0010 1010 1101 0001 0100 1011 • Like soaps, detergents have long hydrocarbon chains, but instead of a carboxylic acid group, have a either a sulfonic acid or phosphoric acid group • These acids form more soluble salts in hard water and lessen the soap scum problem • Problems: pg. 783 1 2 4 Esters: 0011 0010 1010 1101 0001 0100 1011 • Can be thought of as the organic counterparts of salts • Are made from acids, and water is formed in the reaction used to prepare them • However, salts are made from bases and ESTERS are made from alcohols that are not bases but have a hydroxyl group • Uses: perfumes, soaps, fibers, flavoring in drinks, etc. 1 2 4