* Accuracy: Pipettes are calibrated to deliver a specific volume when the liquid is allowed to drain freely. Blowing out the remaining liquid will add to the delivered volume, making your measurement inaccurate.
* Precision: Pipettes are designed to dispense a precise volume, and blowing out the remaining liquid can introduce variability, reducing the precision of your measurements.
* Contamination: Blowing out the remaining liquid can introduce contaminants from your mouth into the solution, compromising the purity and integrity of your experiment.
Exceptions:
There are some specific types of pipettes that are designed to be blown out, such as "to deliver" (TD) pipettes. These pipettes have a specific marking, often a double ring, that indicates you should blow out the remaining liquid. However, most pipettes are "to contain" (TC), meaning they are calibrated to hold a specific volume but not necessarily deliver it completely.
In general, unless the pipette is specifically marked as "to deliver" or you have been instructed otherwise, you should not blow out the remaining liquid in a pipette.
