Determination of Concentration of Strong Acid/Strong Base by Titration

Authors Avatar

I. Introduction: 

The purpose of this experiment was to acquire a more advanced understanding, through active participation, of the process of titration as it is used in the laboratory. To do this, the student preformed two neutralization reactions. The first reaction was between a strong acid with an known concentration and strong base with unknown concentration to determine the concentration of the strong base. The second reaction was between a strong acid with an unknown concentration and strong base with known concentration to determine the concentration of the strong acid. The importance of this experiment lies in determining the concentration of the hydronium ion, [H3O+] or [H+], in aqueous solutions. A strong acid will completely disassociate when dissolved in water to form hydronium ions and the anion. Concentration in this experiment was determined visually through titration with an indicator, phenolphthalein, that turns light pink when the reaction between the two colorless liquids is complete, a point which was subject to judgment of the student. Indicators weak acids or bases that change color if the molecule has gained another acidic proton [H+] and there are more moles of base than acid. A description of concentration in terms of amount of solute is molarity, where the moles of solute is compared to liters of solvent. In this experiment, the acid used was hydrochloric acid, HCl, and the base was sodium hydroxide, NaOH. Two different equations were used in determining molar concentration, or molarity. The first reaction appears as follows:

Join now!

For NaOH, since the molar ratio was  1:1, the following equation was used:

Molarity of HCl was determined using the values from the first experiment and another titration in this equation, the dilution equation, which can be used for titration if there is a

1:1 mole ratio:

 

or

(MNaOH)(VNaOH) = (MHCl)(VHCl)

In both experiments, the average of the results were taken from three trials.

Pre-Lab Questions:

1. Titration: method of quantitative chemical analysis that is used to determine the ...

This is a preview of the whole essay