What kind of burette is used for acid value?

What kind of burette is used for acid value? Titration is one of the oldest quantitative analysis methods.

Titration experiment is also one of the most basic experiments for us majoring in chemistry.

I still clearly remember carefully titrating with a long glass burette, and I was absorbed in the whole experiment. Even if I am so careful, I often doubt that I have not chosen the right destination. Moreover, everyone gets different results in the same experiment, and the seemingly simple manual titration experiment results are greatly influenced by the subjectivity of the operator.

Error source 1

Selection of indicator

Error source 2

Subjectivity of endpoint recognition

Error source 3

Titration volume reading

Automatic potentiometric titration effectively avoids the error caused by subjective judgment in the experiment, and improves the accuracy of titration results through a series of technological innovations such as electronic burette, electrode and operating software.

Operating steps:

1. Take the PH electrode out of the saturated KCL aqueous solution, wash it with distilled water and wipe it clean.

2. Insert the pipette into distilled water and the burette into the waste bottle.

3. Turn on the main engine power supply and the agitator power supply; And start the work program.

4. Click "Parameters" on the working program interface to set parameters and arrange titration settings.

5. Click the "Send" button on the operation page, enter the volume (20-50ml), and press the "Send" button to fill the pipeline with liquid.

6. Look for bubbles. If there are bubbles, insert the needle into the quantitative tube to suck out the gas.

7. Insert the pipette into the standard solution again; Insert the burette into the liquid to be tested, put it on the magnetic stirrer, and put the stirrer into the liquid to be tested. Repeat step 5 above.

8. Insert the cleaned PH electrode into the liquid to be measured, and the tip of the electrode is immersed in the liquid.

9. When the equipotential is basically stable, start the measurement program on the operation interface.

10. At this point, the instrument will draw a curve on the screen during titration. After titration, the instrument will automatically calculate the terminal volume, terminal potential and concentration of the liquid to be measured.

1 1. After the measurement, take out the electrode, clean it, put it back in KCL saturated solution for later use, turn off the titrator and computer, and end the operation.

Precautions:

1, the input end (electrode socket) of the instrument must be kept dry and clean. When the instrument is not in use, insert the Q9 short-circuit plug into the socket to prevent dust and water vapor from invading.

2. When measuring, the lead-in line of the electrode should be kept still, otherwise the measurement will be unstable.

3. When calibrating the instrument with buffer, ensure the reliability of the buffer, and don't mix the buffer by mistake, otherwise the measurement will be inaccurate.

4. After the electrode sleeve is removed, contact between the sensitive glass bubble of the electrode and hard objects should be avoided, because any damage or wiping will make the electrode invalid.

5. For the external reference of composite electrode (or calomel electrode), always pay attention to saturated potassium chloride solution, and add supplementary solution from the small hole at the upper end of the electrode.

6, electrode should avoid long-term immersion in distilled water, protein solution and acid fluoride solution.

7, electrode should avoid contact with silicone oil.

8. Before titration, it is best to rinse the rubber tube of the solenoid valve several times with drops.

9. Do not press the "titration start" button after reaching the end point, or the instrument will start titration again.

10, potassium permanganate and other solutions that work with rubber pipes should not be used.