How to Purge a Burette for a Titration

- Dec 21, 2017 -

How to Purge a Burette for a Titration

To reduce the risk of contamination and miscalculation during a titration, it is always good to rinse and purge your burette. Improperly purged burettes could yield imprecise results, necessitating another titration. Ensure the integrity of your experiments by cleaning your burette properly before and after each use.

Part 1 Preparing the Burette for Titration



Fill the burette with 5 mL of distilled water. Using distilled water is important to keeping your experiment free of impurities and contamination. Fill the burette from the top and try to run the water down the sides when filling to dislodge any particles.[1]

  • Make sure the stopcock is closed (in the horizontal position) before filling the burette.



Tilt the burette horizontally so the water coats the sides of the burette. You want the water to come in contact with as much of the burette side wall as possible without spilling it out of the top.[2]

  • This is the main rinse for the top of the burette. Be sure to swirl the water around the tube thoroughly for each rinse.



Rotate the burette so the water rinses the entire burette. Keeping the burette horizontal, slowly rotate the burette so that the water can rinse the entire inside of the burette.[3]

  • If you see water droplets collecting on the sides of the burette, you may need to more thoroughly clean the burette with glassware detergent.



Tip the burette back to vertical and open the stopcock valve. Once you have the burette back into a vertical position, open the stopcock valve by moving it into the vertical position. Make sure the burette is being held over a sink or waste container as the liquid will drain out of the bottom.[4]



Let about 3 mL of liquid run out the bottom. With the valve open, watch the water level drop until about 3 milliliters (0.1  fl oz) has gone through the tip. This cleans the tip of the burette.[5]

  • Pour the remaining liquid out through the top of the burette.



Close the stopcock and repeat the whole rinse at least two more times. Again, making sure the stopcock is closed, fill the burette with about 5 mL of distilled water. Tilt the burette horizontally and rotate to coat the inside with the water. Back to vertical, let about 3 mL of water out through the bottom tip and then flip the burette to pour out the remaining volume from the top.[6]

  • You want to rinse the burette at least three times with distilled water before use.



Repeat this rinse cycle with the titrant solution. The titrant solution is the solution you will be titrating in the experiment. Using the same method, you want to rinse the burette with this solution so that your results will not be altered by the presence of water in the tube.[7]

  • Rinse the burette 2-3 times with the titrant before beginning your experiment.

  • The titrant rinses are very important to get all of the distilled water out of the burette.

  • Wear gloves with the titrant to avoid contact with harmful chemicals.

Part 2 Preparing the Burette for Storage



Rinse with distilled water after use. Following the end of an experiment, rinse the burette with distilled water at least twice. Fill the burette with 5-10 mLs of water, make sure it coats the tube, and then run the water through the bottom of the tube by opening the stopcock valve.[8]

  • If you were titrating a solution that was highly concentrated, rinse the burette with lots of tap water before moving on to distilled water.



Check for droplets on the side. If you see droplets of water stuck to the side of the burette, the burette is still dirty and needs to be cleaned with more than water. Use a detergent specific for glassware; soak the burette in the detergent and rinse thoroughly.[9]

  • Following cleaning with a detergent, be sure to rinse many times and check for droplet formation on the side. If the burette has been well cleaned, no droplets should form.

  • Let the glassware air dry. Do not dry with towels as they will leave dust behind and contaminate the burette.



Cover the burette top with a paper cap. Once the burette is dry and ready to be put away, it is a good idea to put a paper cap on the top. The cap prevents dust from getting into the burette if it is going to be sitting for a long time.[10]

  • You can make the caps by forming a tube out of paper and then twisting one end.



Store in a glass locker away from dust. All glassware used in the lab should be stored in a glass locker or case. If you have a burette cabinet, make sure the burettes are placed in the correct direction with the stopcock valve placed towards the wall and the burette securely in the hole.[11]

  • Improper placement of burettes can lead to them falling out and breaking when you open the door.

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