Bellringer • What is an acid? • What is a base? • What are some properties of an acid? • What are some properties of a base?
What makes a strong acid or base? • Sulfric acid in a car battery can burn you, but does the citric acid in orange juice? • The strength of an acid or base is based on how many acid or base particles break down into ions in water. • When a strong acid dissolves in water nearly all of the acid molecules will break down into ions • When a weak acid dissolves in water, only a small fraction of the molecules dissolve in water • This is the same for bases • Ions in a solution can conduct electricity, so strong acids and bases will conduct electricity well
Strength vs. Concentration • Strong and weak are terms used to describe how well the substance break down in water • Concentrated or dilute are terms used to indicate the amount of an acid or base dissolved in a solution • It is possible to have a dilute solution of a strong acid or base and a concentrated solution of a weak acid or base
pH of a Solution • pH is the measure of the concentration of hydrogen ions (H+) in a solution • The more hydrogen ions you have in a solution, the lower the pH is and the more acidic the solution is • pH lower than seven is acidic, while pH higher than 7 is basic. pH of 7 is neutral
Measuring pH • Litmus paper is one way to measure pH. The paper undergoes a color change in the presence of hydrogen and hydronium ions. The color is then compared to a chart. • A pH meter uses electrical conductivity to measure pH • Red cabbage juice contains a natural pH indicator. Acids will turn it pink while bases will turn it green
Buffers • Buffers are weak acids or bases that are added to a solution to prevent a change in pH • Buffers are present in your blood to keep the pH between 7 and 7.8