Acid-Base Titration and pH l Aqueous Solution and the Concept of pH – Hydronium Ions and Hydroxide Ions – The pH Scale – Calculating Involving pH l Determining pH and Titrations – Indicators and pH Meters – Titration – Molarity and Titration

Aqueous Solution and pH l Hydronium Ions and Hydroxide Ions – Self-Ionization of Water: water molecules produce Hydronium and Hydroxide ions – Neutral, Acidic, and Basic Solutions Neutral: Hydronium and Hydroxide ions are in equal proportions Acidic: Hydronium ions are in greater concentration than Hydroxide ions Basic: Hydroxide ions are in greater concentration than Hydronium ions – Calculating [H 3 O + ] and [OH - ] K w = [H 3 O + ][OH - ] = [1.0 x M][1.0 x M] = 1.0 x M 2

Aqueous Solution and pH l The pH Scale – Definitions: pH: the negative of the common logarithm of the Hydronium ion concentration [H 3 O + ] pH = -log[H 3 O + ] pOH: the negative of the common logarithm of the Hydroxide ion concentration [OH - ] pOH = -log[OH - ]

Aqueous Solution and pH l The pH Scale – Calculations: pH + pOH = 14.0 –[H 3 O + ][OH - ]=[1.0x10 -7 ][1.0x10 -7 ]=1.0x M 2 Neutral: pH + pOH = 7+7 = 14.0 –[H 3 O + ][OH - ] = [1.0x10 -7 ][1.0x10 -7 ] = 1.0x Acidic: pH + pOH = 14.0, pH < pOH –[H 3 O + ]>[OH - ], [H 3 O + ][OH - ] = 1.0x Basic: pH + pOH = 14.0, pH < pOH –[H 3 O + ]<[OH - ], [H 3 O + ][OH - ] = 1.0x10 -14

Acid-Base Titration and pH l Calculating Involving pH There are as many numbers to the right of the decimal as in the logarithmic quantity – Calculating pH from [H 3 O + ] Use the negative of the exponent to determine the pH – Calculate pH from [H 3 O + ] using a calculator – Calculating [H 3 O + ] and [OH - ] from pH – pH calculations measure the strength of Acids and Bases

Acid-Base Titration and pH l Determining pH and Titrations – Indicators and pH Meters – Titration – Molarity and Titration

Determining pH and Titrations l Indicators and pH Meters – Acid Base indicators: compounds that change color in response to pH – Transitional Interval: the pH range over which an indicator changes color – pH Meter: determines the pH of a solution by measuring the voltage between electrodes

Determining pH and Titrations l Titration – Titration: the controlled addition and measurement of the amount of a solution of a known concentration required to react completely with a measured amount of a solution of unknown concentration. – Equivalence Point: when two titration solutions are in chemically equivalent amounts – End Point: when an indicator within a titration changes color

Determining pH and Titrations l Molarity and Titration – Standard Solution: The solution that contains the precisely known concentration of solute – Primary Standard: The highly purified solid used to check the concentration of a standard