Air bubbles are trapped in burette and tubes. They lead to inaccurate dosing where the system believes the bubble is titrant and gives falsely high results. Furthermore air bubbles of different sizes lead to result variation.
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- How many times should you rinse a buret? Rinse the buret two or three times with the liquid you wish to use. Do this by adding a small amount of liquid into the buret, turning the pipet horizontally and rotating it so that the liquid contacts the entire inside surface of the buret. Let the liquid drain through the stopcock into a waste container.
- Why should the burette be rinsed with NaOH before it is filled? Why do you need to rinse the burette with a base before you completely fill it with NaOH? The burette is designed to make precise volume measurements. The accuracy of a titration depends on precision. If any acidic chemical residue was in the burette, it would neutralize some of the NaOH you are using to measure with.
- Why removal of air bubbles is necessary before titration? Answer and Explanation: Good laboratory technique is critical when manually performing titrations. If you have air bubbles in the burette column, then the initial volume will have an error upon reading since part of that volume is occupied by the bubble rather than the titrant.
- "Why do you clean burette?" If the burette is not completely dry by the time you use it, the remaining traces of water on the inside will make your titrant more dilute and thereby change its concentration.
- Why are the sides of the burette tapped after filling it? After filling the buret with solution, drain a few milliliters of liquid through the stopcock into a beaker to remove any air bubbles trapped in the valve. Close the stopcock, tap the buret sides gently, and allow the liquid to stand for a few minutes to clear gas bubbles dissolved in the liquid.
- Why is it necessary to remove bubbles from the tap and tip of the burette? If an air bubble exits the tip during a titration that volume of air will be registered as some of the volume of titrant that left the buret. This means that the volume of liquid delivered thru the tip will not be the amount calculated by subtracting the final buret reading from the initial buret reading.