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
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