1. Topic: Indicators 1.When the pH of a solution changes from a pH of 5 to a pH of 3, the hydronium ion concentration is 2.As an aqueous solution becomes more acidic, the hydroxide ion concentration 3.Which of the following would have a pH greater than 7 a) HClb) CH 3 OHc) KOHd) NaCl 100 times greater increases

2. How to safely test pH Instruments – use a pH meter Indicators – use a series of indicators See if the substance reacts with a metal other than Cu, Ag, or Au NEVER “ taste ”

3. Indicator substance that changes color over narrow pH range substance that changes color over narrow pH range Use several indicators to narrow down pH range of substance Use several indicators to narrow down pH range of substance Ex: Three samples of the same solution are tested, each with a different indicator. All three indicators, bromthymol blue, bromcresol green and thymol blue, appear blue The pH of the solution must be greater than_____

4. What color would the following indicators be in a neutral solution? yellow green colorless purple blue yellow

5. Practice using table M 1. What indicator is yellow with a pH 9.8 2. Which indictor is blue with a pH of 5.6 0-3.0 4.5-14 3.1.-4.4 Orange Green Pink Purple Green 0-3.7 5.5-14 3.8-5.4 7.7-14 8.4-14 9.7-14