Titration of Acids and Bases

Tran Le

Formal Report

C126 Experimental Chemistry II

Section 8009

Forest Andrews

IUPUI

October 12, 2012

Titration of Acids and Bases

Introduction

According to Arrhenius definition, acid is substance that produces H3O+ ion while base is substance that produces OH- ions. The reaction between acid and base often yields the products of salt and water. The formation of water in this neutralization reaction is caused by the combination of H3O+ and OH- ions.

In order to determine the concentration of an unknown acid and base, a method called acid-base titration is used. The end of the titration has been reached when the moles of acid equals the moles of base. This is called the equivalent point. However, end point os the actual point that is reached in neutralization reaction. End point is signalled by the change in color of the solution because of the presence of pH indicator. The common used indicator is phenolphthalein; it is colorless in acidic solution and pink in basic solution.

In this lab, the concentration of sodium hydroxide (NaOH) was determined by using a known amount of Potassium Hydrogen phthalate (KHP). The balanced chemical equation for the reaction is:

KHC8H4O4(aq) + NaOH(aq) => H2O(l) + KNaC8H4O4(aq) (1)

KHP was chosen as a good acid to standardize NaOH because it has high molecular weight and stable on drying. The standardized NaOH solution was then used to determined the percent composition of KHP in an unknown substance #47.

Experimental Information

Part 1: Standardization of NaOH

NaOH