Standardization of Hydrochloric Acid by Sodium Carbonate Essay Example

a glass rod into a funnel resting in the neck of a clean (but not necessarily dry) 250 cm3 flask.

Wash the beaker out with further small quantities of water, pouring all washings down the rod and funnel into the 250 cm3 flask to ensure that no solution is left on the walls of the beaker. It is as well to remember that once you have weighted out the sodium carbonate into the weighing bottle, every particle of it, whether as solid or as a solution, must be transferred into the 250 cm3 flask. Make up to the mark with water, adding the last few drops from a pipette, and shake well or pour into a large dry beaker in order that the solution may become homogeneous.

By pipette take 25 cm3 of 0.05 M sodium carbonate solution, run it into a conical flask, add two or three drops of screened methyl orange solution, make a note of the burette reading and run in the acid from a burette. The first 15 to 20cm3 of the acid may be run in 5 cm3 at a time without fear of overshooting the end-point. Then run in 1 cm3 at a time, shaking after each addition until the colour changes form yellow to orange. This is a trial titration and its accuracy may not warrant its use in the calculation. The titration should now be repeated with further portions of 25 cm3 of the carbonate solution until two readings are obtained which agree to 0.1 cm3 or three readings which don not show any trend in value, up or down.