Titration

Introduction

There are many types of titration. For example, acid-base titration and redox titration. In this experiment, acid-base titration is carried out. An acid-base titration is a technique that involves using accurate volume measurements to find the concentration of acid or alkali solutions by neutralizing the acid or base with an acid or base of known concentration. Since volume measurements play a key role in titration, it is also known as volumetric analysis. An suitable indicator is used to determine the end point. A good indicator will show a dramatic colour change so that end point of titration can be detect obviously and easily. End point of titration is when the appropriate colour change take place. For weak acid-weak base titration, there is no vertical portion on the curve so no indicator would change colour dramatically. Instead, pH meter is used to monitoring pH. When pH meter is using, equivalent point is determined. Equivalent point is not exactly same as end point as equivalent point is when two reactants mixed in exactly proportions indicated by the equation. The result can be said accurate n reliable when the both end point and equivalent point is close to each other.

Objectives

1. To understand the importance of choosing suitable indicators for detecting the end

point of acid-base titrations.

2. To obtain titration curves for some acid-base titrations.

Materials

Chemicals

0.1M Hydrochloric acid, 0.1M acetic acid, 0.1M sodium hydroxide, 0.1M ammonium hydroxide, phenolphthalein, screened methyl orange, methyl orange.

Apparatus

100mL Beakers, 250mL conical flasks, 50ml burettes, 25ml pipettes, pipette fillers, funnel, pH meters.

Procedure

The experiment was carried out according the procedures from the General Chemistry Practical Manual in page 1 and 2.