What is pH? What is pH? Some of our favorite foods make our - PDF document

4/13/2020 Acids and Bases Acids and Bases What is pH? What is pH?  Some of our favorite foods make our tongue curl up because they are SOUR. 1 2 Bitter! Acidic/Basic  Some foods have a  There is a scientific reason for this: “bite” of their own  These foods are either acidic or basic. because they’re  Other substances besides foods have somewhat bitter. these characteristics.  WHY? 3 4  Some Acids and Bases Acids and Bases substances are not really  Chemicals may be classed as acids or an acid or a bases. base: For  Things that are neither acids nor bases example, pure water are neutral.  pH measures how acidic or basic a solution is. 5 6 1

4/13/2020  A special name is given to the Most Substances: pH acid or base characteristic that a substance has:  Can be identified as  It is called: pH either acidic or basic  “p” stands for potential and  Like the soil in our “H” stands for hydrogen; backyard. hence, the potential of a substance to attract hydrogen ions 7 8 How Does It Work? How Do We Measure pH?  The paper is treated with chemicals that change  We measure pH by color to show the pH. using special strips of  When the paper touches paper called pH paper the substance being tested, it turns a specific or litmus paper. color to tell if the substance is an acid or a base. 9 10 The pH Scale Acid  pH scale ranges from 0 -14  pH 7 is neutral; neither acid nor base  Any substance which has a pH of value of  Pure water is pH 7 less than 7 is considered an acid  Low pH (0-6.9) = acid  High pH (7.1-14) = base 0--------------7---------------14  The closer to the ends of the scale, the Acid Neutral Base stronger the solution is 11 12 2

4/13/2020 Base pH 7  Any substance which has pH value greater  A pH of 7 is called neutral—neither acid than 7 is a base nor base. 0--------------7---------------14 0------------7------------14 Acid Neutral Base Acid Neutral Base 13 14 The pH Scale Acidic or Basic  If the number is less than 7 the substance is acidic  If the number is more than 7 the substance is basic 15 16 The pH Scale The pH Scale  Each pH unit is 10 times as large as the  Each pH unit is 10 times as large as the  Careful measurement is important previous one previous one  A mistake of one pH unit means 10 times  A change of 2 pH units means 100 times more  A change of 2 pH units means 100 times more too much or too little! basic or acidic basic or acidic x10 x100 x10 x100 17 18 3