a 000 mL of NaOH added What is in the flask calculate the pH Initial pH K a 3 H

# A 000 ml of naoh added what is in the flask calculate

This preview shows page 7 - 11 out of 13 pages.

a. 0.00 mL of NaOH added - What is in the flask? - calculate the pH: Initial pH: K a = 3 H O A HA     pH = –log[H 3 O + ] Chem 1036 Chapter 19 28 of 51 b. 10.0 mL of NaOH added: - What is in the flask? Do the stoichiometry: HC 3 H 5 O 2 ( aq ) + OH ( aq ) H 2 O( l ) + C 3 H 5 O 2 ( aq ) - Calculate the pH: pH before the equivalence point: a [base] pH p log [acid] K Chem 1036 Chapter 19 29 of 51 c. 20.0 mL of NaOH added: - What is in the flask? Do the stoichiometry HC 3 H 5 O 2 ( aq ) + OH ( aq ) H 2 O( l ) + C 3 H 5 O 2 ( aq ) - Calculate the pH Chem 1036 Chapter 19 30 of 51 d. 40.0 mL of NaOH added: - What is in the flask? Do the stoichiometry HC 3 H 5 O 2 ( aq ) + OH ( aq ) H 2 O( l ) + C 3 H 5 O 2 ( aq ) - Calculate the pH Chem 1036 Chapter 19 31 of 51 pH at the equivalence point: A ( aq ) + H 2 O( l ) HA( aq ) + OH ( aq ) conjugate base produced during titration K b = HA OH A Where [A ] = initial acid base HA V + V and K b = w a K K pOH = –log[OH ] pH = 14.00 – pOH Chem 1036 Chapter 19 32 of 51 e. 50.0 mL of NaOH added: - What is in the flask? Do the stoichiometry HC 3 H 5 O 2 ( aq ) + OH ( aq ) H 2 O( l ) + C 3 H 5 O 2 ( aq ) - Calculate the pH Chem 1036 Chapter 19 33 of 51 Chem 1036 Chapter 19 34 of 51 3. Strong Acid-Weak Base Titration B( aq ) + H + ( aq ) BH + ( aq ) Weak base Conjugate weak acid Equilibrium calculations will be required to find the pH of a solution of a weak acid and/or weak base. NH 3 ( aq ) + H + ( aq ) NH 4 + ( aq ) 1. Before adding any strong acid titrant: . Initial pH: K b = BH OH B     pOH = –log[OH ] pH = 14.00 – pOH Chem 1036 Chapter 19 35 of 51 2. After strong acid titrant is added but before the equivalence point is reached: the solution contains a buffer: 3. At the equivalence point at which all weak base has been consumed and the solution contains the conjugate weak acid: pH before the equivalence point: a [base] pH p log [acid] K pH at the equivalence point: BH + ( aq ) + H 2 O( l ) B( aq ) + H 3 O + ( aq ) K a = 3 B H O BH Where [BH + ] = initial acid base B V + V and K a = w b K K pH = –log[H 3 O + ] Chem 1036 Chapter 19 36 of 51 Chem 1036 Chapter 19 37 of 51 Characteristics of Acid-Base Titrations (Spectator ions marked in bold ) Strong acid-strong base titration Weak acid-strong base titration Strong acid-weak base titration Example H NO 3 + K OH H 2 O + K + + NO 3 HF + K OH H 2 O + K + + F H NO 3 + NH 3 NH 4 + + NO 3 Species present at the equivalence point H 2 O and spectator ions H 2 O, conjugate weak base and spectator cation Conjugate weak acid and spectator anion pH at equivalence point 7.0 > 7.0 < 7.0 Chem 1036 Chapter 19 38 of 51 Acid-Base Indicators Acid-Base Indicators: HIn( aq ) H + ( aq ) + In ( aq ) Acid form (one color) Base form (different color) As the titration proceeds, H + is either added or removed and the equilibrium shifts to either produce more HIn or to produce more In .  #### You've reached the end of your free preview.

Want to read all 13 pages?

• • •  