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Correct!
Correct!
To titrate sulfurous acid, H2SO3, you should add a base of known concentration.
Calibrate the Vernier apparatus
Calibrate the Vernier apparatus
Start by calibrating the pH sensor to ensure the readings are accurate.
Next, rinse the reservoir with 4-5 mL of titrant and check the apparatus for leaks, then calibrate the drop counter according to the instructions in Appendix IV of your lab manual.
Pour 25.0 mL of 0.020 M H2SO3 into a clean, dry 150 mL beaker and label it.
How much titrant will it take to reach the first equivalence point?
Rinse the tip of the electrode using distilled water and blot dry with a Kimwipe.
rinsing pH sensor
Place a magnetic stir bar into the beaker containing the 0.020M H2SO3. Place the beaker onto the magnetic stir plate with the pH sensor submerged in the sample. Adjust the height of the pH sensor so that it does not come into contact with the stir bar but is still submerged in the sample solution.
Turn on the stir plate so that the stir bar is stirring the solution.
Sample of 0.020 M H2SO3 with
a stir bar and pH probe.
Sample of 0.020 M H2SO3 with
an active stir bar and pH probe.
Be careful not to adjust the position of the drop counter or titrant reservoir as you add the stir bar to the sample and position the stir plate. If you do move the drop counter or reservoir, the alignment setup steps need to be repeated.
If the stir plate also has a heating function, make sure that the heat setting is turned OFF.
Hot plate with the heating function active.
Hot plate with the heating function turned off.
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