Lab 20- Acids & Bases Titration

A. Neutralization Chemical reaction between an acid and a base. Products are a salt (ionic compound) and water.

ACID + BASE  SALT + WATER Neutralization ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H2O strong strong neutral HC2H3O2 + NaOH  NaC2H3O2 + H2O weak strong basic Salts can be neutral, acidic, or basic. Neutralization does not mean pH = 7.

Titration standard solution unknown solution Titration Analytical method in which a standard solution is used to determine the concentration of an unknown solution.

B. Titration Equivalence point (endpoint) Point at which equal amounts of H3O+ and OH- have been added. Determined by… indicator color change dramatic change in pH

moles H3O+ = moles OH- MV n = MV n B. Titration M: Molarity V: volume n: # of H+ ions in the acid or OH- ions in the base

B. Titration 42.5 mL of 1.3M NaOH are required to neutralize 50.0 mL of KHP. Find the molarity of KHP. H3O+ M = ? V = 50.0 mL n = 1 OH- M = 1.3M V = 42.5 mL n = 1 MV = MV M(50.0mL) =(1.3M)(42.5mL) M = 1.11 M H2SO4

Procedures Data you need for part A KHP =204.2g/mol Formulas M = mol/liters moles H3O+ = moles OH- MV (H3O+) = MV (OH-) % KHP = mass of KHP/ Mass of mixture

Procedures A. Standardization of NaOH Add 2.5 grams of KHP into 3 Erlenmeyer flasks Use analytical balance to 4 sig figs Add 100 ml of D.I water into each flask Add 2 drops of Phenolphthalein soln

Slowly add NaOH into 1st flask, while swirling flask A. Fill a Burett with NaOH (aq) Slowly add NaOH into 1st flask, while swirling flask See fig 20-2 and read procedures for proper titration Record amount of NaOH used to titrate

calculations Determine moles of KHp Determine moles of NaOH Determine Molarity of NaOH Determine Standard deviation (do this at home, see pgs 80 - 82)

Part B . Standardization of unKnown acid Add 2.5 grams of unknown acid into 3 Erlenmeyer flasks Use analytical balance to 4 sig figs Add 100 ml of D.I water into each flask Add 2 drops of Phenolphthalein soln

Slowly add NaOH into 1st flask, while swirling flask A. Fill a Burett with standarized NaOH Slowly add NaOH into 1st flask, while swirling flask See fig 20-2 and read procedures for proper titration Record amount of NaOH used to titrate

calculations Determine moles of base used Determine moles of KHP Determine mass of KHp Determine % of KHP in unknown