Tag Archives: acid-base titration
Microtitrations
The illustrations below show two approaches to titrating very small samples. In the first experimental design, samples of 20–100 µL were held by capillary action between a flat-surface pH electrode and a stainless steel sample stage. The titrant was added by … Continue reading
Limitations to Acid-Base Titrations
In an acid–base titration the volume of titrant needed to reach the equivalence point is proportional to the moles of titrand. Because the pH of the titrand or the titrant is a function of its concentration, however, the change in … Continue reading
Determining an Acid Dissociation Constant from a Titration
Another application of acid–base titrimetry is the determination of equilibrium constants. Consider, for example, a solution of acetic acid, CH3COOH, for which the dissociation constant is Ka = [H3O+][CH3COO–]/[CH3COOH] When the concentrations of CH3COOH and CH3COO– are equal, the Ka expression reduces … Continue reading
Finding the Equivalence Point From a Titration Curve
An alternative to using a visual indicator to locate a titration’s end point is to continuously monitor the titration’s progress using a sensor whose signal is a function of the analyte’s concentration. The result is a plot of the entire … Continue reading
Visual Indicators for Acid-Base Titrations
The illustration below shows the relationship between pH and an indicator’s color. The ladder diagram defines pH values where each of the indicator’s two forms the weak acid form, HIn, which in this example is yellow the weak base form, … Continue reading
Locating a Titration’s Equivalence Point
For most acid–base titrations the inflection point, the point on a titration curve having the greatest slope, very nearly coincides with the equivalence point. The red arrows in the following figure for example, indicate the equivalence points for the titrations … Continue reading