Standardizing A Solution Of Sodium Hydroxide

Submitted By Sp790880O
Words: 655
Pages: 3

Selena Prado
December 9, 2014
AP Chemistry

Standardizing a Solution of Sodium Hydroxide PURPOSE:
To determine the concentration of sodium hydroxide.

● ∙ Prepare an aqueous solution of sodium hydroxide to a target molar concentration.

● ∙ Determine the concentration of your NaOH solution by titrating it with a solution of potassium hydrogen phthalate, abbreviated KHP, of precise molar concentration.

LabPro or CBL 2 interface

solid sodium hydroxide

computer or handheld

solid potassium hydrogen phthalate, KHP

Vernier pH Sensor

distilled water

ring stand

plastic weighing dish or weighing paper

250 mL beaker


250 mL Erlenmeyer flask

utility clamp

50 mL and 100 mL graduated cylinders

buret and buret clamp

magnetic stirrer and stirring bar

100 mL graduated cylinder

1. Measure out 100.00 mL of distilled water into a 250 mL Erlenmeyer flask. 2. Set up the data collection system. Connect a LabPro or CBL 2 interface to the computer or handheld with the proper cable.
Connect the pH Sensor to Channel 1 of the interface.
Start the data collection program.
Set up data collection for Events with Entry mode.

3. Measure out the mass of NaOH that is needed to prepare a 0.10 M solution and add it to the flask of distilled water. Swirl the flask to dissolve the solid. CAUTION: Sodium hydroxide solution is caustic. Avoid spilling it on your skin or clothing. 4. Measure out the mass of KHP that will neutralize 25 mL of 0.10 M NaOH solution.
Dissolve the KHP in about 50 mL of distilled water in a 250 mL beaker. 5. Set up a ring stand, buret clamp, and buret to conduct a titration (see Figure 1). Place a utility clamp on the ring stand to hold the pH Sensor in place during the titration. 6. Rinse and fill the buret with the NaOH solution. Place a magnetic stirring bar in the beaker and place the beaker of KHP solution on a magnetic stirrer under the buret. Connect the pH Sensor to the utility clamp so that the tip of the sensor in immersed in the KHP solution but does not interfere with the movement of the magnetic stirring bar. 7. Conduct the titration carefully. When you have completed the titration, dispose of the reaction mixture as directed. Before conducting a second titration you may wish to print a copy of the results of your first titration, save the data, or record your data in a table or chart. 8. Use your titration data to find the equivalence point, which is the largest increase in pH upon the addition of a very small amount of NaOH solution. A good method of determining the precise equivalence point of the titration is to take the second derivative of the pH­volume data, a plot of D2pH/Dvol2. 9. Repeat the titration with a second