1. SOLUTION STOICHIOMETRY LECTURE 3 ACIDS AND BASES

2. Arrhenius Acids Acids Give off H + Give off H + Bases Bases Give off OH - Give off OH - Substances that caused a problem??? Substances that caused a problem??? Main example – NH 3 Main example – NH 3

3. Brønsted-Lowry Came up with new definition to account for these Came up with new definition to account for these Acids Acids Give off (donate) protons (H + ) Give off (donate) protons (H + ) Bases Bases Accept protons (H + ) Accept protons (H + ) Remember conjugates?? Remember conjugates??

4. Neutralization A special type of double replacement reaction A special type of double replacement reaction Reactants = Reactants = Acid Acid Base Base Products Products Water Water A salt (ionic compound) A salt (ionic compound)

5. Neutralization

6. Strong Acid + Strong Base Hydrochloric acid (aq) + sodium hydroxide (aq) Hydrochloric acid (aq) + sodium hydroxide (aq) Demo Demo Molecular Molecular HCl (aq) + NaOH (aq) --> NaCl (aq) + HOH (l) HCl (aq) + NaOH (aq) --> NaCl (aq) + HOH (l) Complete Ionic Complete Ionic H + (aq) + Cl - (aq) + Na + (aq) + OH - (aq) --> Na + (aq) + Cl - (aq) + HOH (l) H + (aq) + Cl - (aq) + Na + (aq) + OH - (aq) --> Na + (aq) + Cl - (aq) + HOH (l) Net Ionic Net Ionic H + (aq) + OH - (aq) --> HOH (l) H + (aq) + OH - (aq) --> HOH (l) Formation of water

7. Weak Acid + Strong Base Acetic acid (aq) + potassium hydroxide (aq) Acetic acid (aq) + potassium hydroxide (aq) Molecular Molecular HC 2 H 3 O 2 (aq) + KOH (aq) --> KC 2 H 3 O 2 (aq) + HOH (l) HC 2 H 3 O 2 (aq) + KOH (aq) --> KC 2 H 3 O 2 (aq) + HOH (l) Complete Ionic Complete Ionic HC 2 H 3 O 2 (aq) + K + (aq) + OH - (aq) --> K + (aq) + C 2 H 3 O 2 - (aq) + HOH (l) HC 2 H 3 O 2 (aq) + K + (aq) + OH - (aq) --> K + (aq) + C 2 H 3 O 2 - (aq) + HOH (l) Net Ionic Net Ionic HC 2 H 3 O 2 (aq) + OH - (aq) --> C 2 H 3 O 2 - (aq) + HOH (l) HC 2 H 3 O 2 (aq) + OH - (aq) --> C 2 H 3 O 2 - (aq) + HOH (l)

8. Stoichiometry 1. Write equations. 2. Balance net ionic equation. 3. Find moles (from original solutions). 4. Limiting reactant 5. Mole ratio 6. Get it out of moles  Example -  How many grams of water are formed when 50.0 mL of 0.356 M HI react with 28.0 mL of 0.488 M barium hydroxide?

9. Titration Delivery with a buret of a known solution (titrant) into an unknown solution (titrate or analyte) until the endpoint or equivalence point Delivery with a buret of a known solution (titrant) into an unknown solution (titrate or analyte) until the endpoint or equivalence point Vocabulary Vocabulary Titrant = solution of known concentration, in buret Titrant = solution of known concentration, in buret Titrate = solution of unknown concentration, in beaker Titrate = solution of unknown concentration, in beaker Endpoint = point where an indicator first changes color, titrant exactly reacted with the titrate Endpoint = point where an indicator first changes color, titrant exactly reacted with the titrate Equivalence point = HUGE!!! Equivalence point = HUGE!!! Demo = iron ions and permanganate (we’ll do it for real later in the year & simulated) Demo = iron ions and permanganate (we’ll do it for real later in the year & simulated) http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/redoxNew/redox.html

10. HUGE POINT Equivalence point Equivalence point Occurs when MOLES = MOLES (stoichiometrically) Occurs when MOLES = MOLES (stoichiometrically) Really important for titration calculations!!

11. Example Titration Problem from AP exam 0.2640 g of sodium oxalate is dissolved in a flask and requires 30.74 mL of potassium permanganate (from a buret) to titrate it and cause it to turn pink (the end point). 0.2640 g of sodium oxalate is dissolved in a flask and requires 30.74 mL of potassium permanganate (from a buret) to titrate it and cause it to turn pink (the end point). The equation for this reaction is: 5 Na 2 C 2 O 4 (aq) + 2 KMnO 4 (aq) + 8 H 2 SO 4 (aq)  5 Na 2 C 2 O 4 (aq) + 2 KMnO 4 (aq) + 8 H 2 SO 4 (aq)  2 MnSO 4 (aq) + K 2 SO 4 (aq) + 5 Na 2 SO 4 (aq) + 10 CO 2 (g) + 8 H 2 O (l) (a) How many moles of sodium oxalate are present in the flask? (b) How many moles of potassium permanganate have been titrated into the flask to reach the end point? (c) What is the molarity of the potassium permanganate?