Hydrochloric Acid Base Titration

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Aim: The aim of this experiment is to monitor the pH change using a pH meter and data logger as HCl is titrated with NaOH and to then determine the molarity of the HCl solution.
Introduction
A titration is an analytical method in which the unknown concentration of a solution, analyte, is calculated by determining the volume of a solution with known concentration needed, titrant, to completely react with the analyte. In this case the hydrochloric acid solution (HCl) is the analyte since its concentration is unknown and it is titrated with sodium hydroxide (NaOH) which serves as a titrant since its concentration is known. This is as an acid-base titration and in it the hydrogen ions from the HCl react with hydroxide ions from the NaOH to produce …show more content…

As the base, NaOH, is added drop by drop the pH gradually increases until the equivalence point. This is when the amount of hydroxide ions (from base) added equals to the amount of hydrogen ions (from acid) present in the solution. At this point the pH increases very rapidly until it reaches a more gradual rate of increase.
The pH change can be followed using a pH meter and measuring the pH after each drop of base added. Then, plotting a pH versus volume of base graph the volume at equivalence point can be determined. The curve of a strong acid-base titration is shown in Figure 1.0.
Figure 1.0 – The titration curve obtained when plotting the pH versus volume of base added during a strong acid-base titration. Objectives: Use a pH Sensor to monitor changes in pH during a titration of HCl with …show more content…

The burette is attached to a laboratory stand with 2 clamps. The burette is first rinsed with 0.1M NaOH and then it is filled with it a bit above the 0.00 mL mark. NaOH is drained from the burette so that there are not bubbles in the tip and so that the NaOH reaches exactly the 0.00 mL level. Dispose of the waste NaOH solution that was drained. 50 mL of distilled water is added to the 250 mL beaker and 10 mL of HCl is pipetted into the beaker. The beaker is placed on the magnetic stirrer and a stirring bar is placed inside the solution. The beaker and the magnetic stirrer are placed under the burette. The support ring is attached to the laboratory stand and a pH Sensor is positioned on it so that it is immersed in the HCl solution. Make sure the stirrer will not hit the pH probe. Turn on the magnetic stirrer and adjust it to medium stirring (no splashing). Connect the pH Sensor to the Vernier computer

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