Section 20.4 Neutralization Reactions OBJECTIVES: Define the products of an acid-base reaction.

Section 20.4 Neutralization Reactions OBJECTIVES: Explain how acid-base titration is used to calculate the concentration of an acid or a base.

Section 20.4 Neutralization Reactions OBJECTIVES: Explain the concept of equivalence in neutralization reactions.

Section 20.4 Neutralization Reactions OBJECTIVES: Describe the relationship between equivalence point and the end point of a titration.

Acid-Base Reactions Acid + Base Water + Salt Properties related to every day: antacids depend on neutralization farmers adjust the soil pH formation of cave stalactites human body kidney stones from insoluble salts

Ch. 21 Notes -- Neutralization Neutralization Reactions When an acid and base are mixed, the _______ of the acid and the __________ of the base combine to form ___________. The _____________ (negative ion) of the acid and the _________ (positive ion) of the base come together to form a ___________. A salt is defined as ________________ (metal plus a nonmetal) compound that can formed by acid-base neutralization. All neutralization reactions are simple ___________ replacement reactions. 1 Mole of H+ ions exactly neutralizes 1 Mole of OH- ions. H+1 OH-1 water anion cation salt ionic double H2O HX + M(OH)  ______ + ______ MX (“Salt”)

Completing Neutralization Reactions Examples: (1) Complete the following neutralization reactions. HCl (aq) + NaOH (aq)  _________ + __________ HNO3 (aq) + Ca(OH)2 (aq)  __________ + ________ H2SO4 (aq) + KOH (aq)  _________ + __________ Practice Problems: See if you can complete these on your own. HNO3 (aq) + KOH (aq)  __________ + __________ HCl (aq) + Ca(OH)2 (aq)  __________ + __________ NaCl H2O +2 −1 Ca(NO3)2 H2O 2 2 2 K2SO4 H2O 2

Titration Mixing an acid with a base to determine the ______________ is called “titration.” An ____________ is used to determine when neutralization has occurred. ________________ Solution - the solution of known concentration ______ _________ - the point of neutralization when titrating. When the [H+] ions = [OH−] ions. _______ point is when the indicator changes color. concentration indicator Standard Equivalence Point End Click Here to Watch Titration Video on YouTube

Determining the Concentration of an Acid (or Base) by Titration (Macid)x(Vacid) = (Mbase)x(Vbase) Practice Problems: (1) A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO3 solution? (2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of a 0.76 M HCl standard solution? ( ) x ( ) = ( ) x ( ) Macid 25 mL 1.0 M 18 mL Macid = 0.72 Molar ( ) x ( ) = ( ) x ( ) 0.76 M 55 mL 2.0 M Vbase Vbase = 20.9 mL

Titration The concentration of acid (or base) in solution can be determined by performing a neutralization reaction An indicator is used to show when neutralization has occurred Often we use phenolphthalein- because it is colorless in neutral and acid; turns pink in base

Steps - Neutralization reaction #1. A measured volume of acid of unknown concentration is added to a flask #2. Several drops of indicator added #3. A base of known concentration is slowly added, until the indicator changes color; measure the volume

Neutralization The solution of known concentration is called the standard solution added by using a buret Continue adding until the indicator changes color called the “end point” of the titration