Neutralization & Titration Monday, May 8th, 2017

Warm-Up Identify the acid and base in the following equation using one of the theories we learned. What is the pH of a solution with a hydrogen ion concentration of 2.83 x 10-3 M? What is the pH of a solution with a hydroxide ion concentration [OH-] = 8.45 x 10-6?

Identify the acid and base in the following equation using one of the theories we learned. HNO2 is an Arrhenius Acid because in the presence of water it creates hydronium (H3O+) ions. Water is the base. HNO2 is a Bronsted-Lowry Acid because it donates a proton. H2O is the base because it accepts the proton. HNO2 is a Lewis acid because it accepts an electron pair. H2O is a Lewis base because it donates an electron pair.

pH = -log [H+] pH = -log (2.83 x 10-3) pH = 2.55 2. What is the pH of a solution with a hydrogen ion concentration of 2.83 x 10-3 M? pH = -log [H+] pH = -log (2.83 x 10-3) pH = 2.55

3. What is the pH of a solution with a hydroxide ion concentration [OH-] = 8.45 x 10-6? pOH = -log [OH-] pOH = -log(8.45x10-6) = 5.07 pH + pOH = 14 14 – pOH = pH = 14 – 5.07 pH = 8.93

When can a chemical reaction result in a neutral solution: Moles hydrogen ions = moles hydroxide ion *Notice it does not say moles acid = moles base* WHY? Because when water dissociates moles H+ = moles OH- Acid + Base  Salt + Water HCl (aq) + NaOH  NaCl (aq) + H2O H2SO4 (aq) + 2KOH  K2SO4 (aq) + 2H2O What type of chemical reactions are these?

Predict what salt you would get if these acids and bases reacted: H2SO4 (aq) + Ba(OH)2  ______________ + H2O HBr (aq) + AgOH  _____________ + H2O Nitric acid mixed with lithium hydroxide makes… Calcium hydroxide mixed with sulfuric acid makes….

Strong Acid + Strong Base  Salt + Water When mixing acids and bases you ALWAYS get a salt and water however you do not always gets a neutral solution Neutral solutions result only when you have added equal moles of H+ (hydrogen ions) and OH- (hydroxide ions) from strong acids and strong bases. Strong Acid + Strong Base  Salt + Water (neutral solution)

Neutralization: The process where an acid and a base react to make a neutral solution HNO3 + LiOH  LiNO3 + H2O Ca(OH)2 + H2SO4  CaSO4 + 2H2O It is important to be able to calculate the amount of H+ and OH- from acids and bases because not all are created equal! Strong acids versus weak acids have DIFFERENT MOLE RATIOS!

HCl (aq) + NaOH  NaCl (aq) + H2O In your notebook – calculate the moles of base required to neutralize 1.0 L of 0.10M of each acid below: HCl (aq) + NaOH  NaCl (aq) + H2O H2SO4 (aq) + 2KOH  K2SO4 (aq) + 2H2O H2SO4 (aq) + Ca(OH)2 (aq)  CaSO4 (aq) + 2H2O 4. What volume of 0.050M sodium hydroxide is required to neutralize 10.0mL of 0.100M of hydrochloric acid?

HCl (aq) + NaOH  NaCl (aq) + H2O 0.1 M = x mol 1 L mol HCl = 0.1 mol HCl x 1 mol NaOH 1 mol HCl = 0.1 mol NaOH

2. H2SO4 (aq) + 2KOH  K2SO4 (aq) + 2H2O 0.1 mol H2SO4 x 2 mol KOH 1 mol H2SO4 = 0.2 mol KOH

3. H2SO4 (aq) + Ca(OH)2 (aq)  CaSO4 (aq) + 2H2O 0.1 mol H2SO4 x 1 mol Ca(OH)2 1 mol H2SO4 = 0.1 mol Ca(OH)2

mol HCl: mol = M x L= 0.100M x 0.01 L = 0.001 mol HCl 4. What volume of 0.050M sodium hydroxide is required to neutralize 10.0mL of 0.100M of hydrochloric acid? HCl + NaOH  NaCl + H2O mol HCl: mol = M x L= 0.100M x 0.01 L = 0.001 mol HCl 0.001 mol HCl x 1 mol NaOH 1 mol HCl = 0.001 mol NaOH L = mol/M = 0.001 mol/0.05 M = 0.02 L

Titration Used to determine the unknown concentration of a solution An indicator is used to show endpoint (point of neutralization when moles H+ = moles OH-)

For 1:1 Neutralizing Reactions HCl + NaOH  NaCl + H2O Moles H+ = Moles OH- Moles = molarity x volume How many mL of a 0.050M NaOH solution are required to neutralize 20.0mL of 0.100 M HCl? MAVA = MBVB