Why is a rubber safety bulb preferred over using one's mouth when working with a pipet?

Using a rubber safety bulb to create suction with a pipet is preferred primarily because it allows for suction to be generated without any direct contact with the liquid being transferred. This method significantly reduces the risk of contamination both of the liquid sample and the person using the pipet. By using a safety bulb, you prevent any possibility of liquid entering the mouth, which can pose both health hazards and contamination risks.

Additionally, employing a safety bulb is a hygienic practice in a lab setting, ensuring that samples remain uncontaminated by saliva or other substances that may be present in the mouth. This is especially important in chemistry labs, where chemicals can be hazardous or toxic. Therefore, choosing the safety bulb method not only enhances safety but also maintains the integrity of the samples being worked with.