High-Tech Titration
Use titration to discover the concentration of a solution of hydrochloric acid.
PASPORT pH Sensor
(PS-2102)
ScienceWorkshop pH Sensor
(CI-6507A)
Lab Summary
Students will use titration to discover the concentration of a solution of hydrochloric acid.
When acids and bases react in typical neutralization reactions, each chemical species supplies either hydroxide ions (OH-) or protons (H+) to the solution. Water molecules accept the protons to form hydronium ions (H3O+), which react in a one-to-one ratio with the hydroxide ions supplied by the base. One mole of hydroxide ions is therefore chemically equivalent to one mole of hydronium ions. As neutralization occurs, the pH of the solution changes. In order to determine when chemically equivalent amounts of acid and base are present, chemists use the process of titration. A solution of known concentration (the titrant) is carefully measured and added gradually to a solution of unknown concentration, and the resulting pH is monitored. The equivalence point of the titration is the point at which chemically equivalent amounts of acid and base are present. A pH meter or sensor will show a large voltage change at the equivalence point. Alternatively, a well-chosen indicator will change color at the equivalence point, as long as it changes color over the same range as the equivalence point. Knowing the volume of titrant at the equivalence point, along with knowledge of the stoichiometry of the reaction, allows the chemist to calculate the concentration of the unknown solution.
Hypothesize: Since the pH of the solution will change most dramatically at the equivalence point, predict the shape of the graph that will result when pH is plotted vs. volume of titrant for the reaction between a strong acid and a strong base. What pH might the equivalence point be close to?
Published: March 2003
Downloads
- High-Tech Titration - PASPORT (20 KB, .zip)
Includes experiment setup, procedures and Datastudio file
- High-Tech Titration - ScienceWorkshop (20 KB, .zip)
Includes experiment setup, procedures and Datastudio file
Here's What You Need
U.S. Educator prices shown.
Probeware (PASPORT Systems)
Xplorer GLX (PS-2002) - $349
The Xplorer GLX is a data collection, graphing, and analysis tool designed for science students and educators.
PASPORT pH Sensor (PS-2102) - $79
Has a wide measurement range of 0 to 14 pH. Has a resolution of 0.01 pH. For use with PASPORT Interfaces.
Probeware (ScienceWorkshop Systems)
750 Interface, USB (CI-7650) - $679
The 750 Interface allows students to measure force, temperature, pressure, angular velocity, acceleration, current, and magnetic field with a built-in function generator and oscilloscope mode.
Other Materials
- 0.1 M sodium hydroxide solution (NaOH), approximately 60 mL
- HCl of unknown concentration, 10 mL
- Distilled water, 50 mL
- Lab glassware: 10-mL pipette, 100-mL graduated cylinder, 250-mL beaker, 50-mL buret
- Base and support rod and 2 buret clamps
- Recommended: magnetic stirrer and stir bar
- Wash bottle of distilled water
- Protective gear: goggles, lab aprons
