Mrs. Brostrom Integrated Science  An acid is any compound that increases the number of hydronium ions (H3O+) when dissolved in water  The hydronium ion forms when a H ion (H+) separates from the acid and bonds with a water molecule (H2O) H3O+ → H+ + H2O  A sour flavor Lemons, limes, vinegar  However, taste should never be used to identify acids  Some can be corrosive and poisonous   Change color in indicators   A substance that changes color in the presence of an acid or base is an indicator Litmus is a common indicator used to detect the strength of acids  When an acid is added to blue litmus paper, the color changes to red React with metals to produce hydrogen gas Ex.) Hydrochloric acid reacts with zinc to produce hydrogen gas • 2HCl + Zn → H2 + ZnCl2  Conduct electric current   When acids dissolve in water, they break apart and form ions Ex.) Car battery contains sulfuric acid  Used in industry and homes Sulfuric acid is most widely used industrial chemical; paper paint detergents, and fertilizers  Nitric acid; fertilizers, rubber, and plastics  Hydrochloric acid is used to make metals from their ores (by separating them), swimming pools, stomach  Hydrofluoric acid is used to etch glass  Citric acid and ascorbic acid are found in orange juice  Carbonic acid and phosphorous acid are found in soda   A base is any compound that increases the number of hydroxide ions (OH-) when dissolved in water  Ex.) Sodium hydroxide breaks apart to form sodium ions and hydroxide ions NaOH → Na+ + OH-  Bitter taste   Taste should never be used to identify a base, like acids they are corrosive Slippery feel  Ex.) Soap  Bases change colors in indicators  Like acids, litmus is a common indicator used to detect the strength of bases  Bases change the color of red litmus paper to blue  Bases conduct electric current  Bases increase the number of hydroxide ions (OH-) which has a negative charge     Sodium hydroxide, used to make soap, paper, oven cleaners, drain cleaners Calcium hydroxide, used to make cement and plaster Ammonia, found in many household cleaners and used to make fertilizer Magnesium hydroxide and aluminum hydroxide, used in antacids Mrs. Brostrom Integrated Science   Strength of acids and bases are not the same as concentration As an acid dissolves in water, the molecules break apart producing hydrogen ions (H+). If all the molecules break apart, the acid is called strong acid.  Strong acids include sulfuric acid, nitric acid, and hydrochloric acid • If only a few molecules break apart, it is a weak acid.  Weak acids include acetic acid, citric acid, and carbonic acid  When all of the molecules of a base break apart in water to produce hydroxide ions (OH-)the base is a strong base Sodium hydroxide, calcium hydroxide, and potassium hydroxide • When only a few molecules break apart it is a weak base  Ex.) Ammonium hydroxide and aluminum hydroxide    The reactions between acids and bases is a neutralization reaction The hydrogen ions (H+) that are present in an acid and the hydroxide ions (OH-) that are present in a base react to form water H+ + OH- → H2O • The other ions in the acids and base dissolve in the water and if it evaporates, bond together to produce salt  The pH of a solution is a measure of the hydronium ion concentration in a solution    pH of 7 is neutral (neither acid or base); pure water Basic solutions have a pH greater than 7 Acidic solutions have a pH less than 7  pH can be measured using pH (litmus) paper  pH meter • Living things depend on having a steady pH - lettuce needs basic soil; between 8 and 9 • Most rain has a pH between 5.5 and 6    When an acid neutralizes a base, water and salt is produced A salt is an ionic compound formed from the positive ion of a base and the negative ion of an acid   NaCl, used to season food Sodium nitrate, used to preserve food HCl + NaOH → H2O + NaCl