Question

1aYou are measuring 10.00mL of liquid with a volumetric pipet. While you are drawing the liquid into the pipet, you remove the tip of the pipet from the solution and suck up a little bit of air into the pipet. You adjust the liquid so that the meniscus is at the calibration line, but you notice there are some air bubbles in the pipet.

1a.) How do the bubbles impact the amount of liquid that you will dispense? Will you have more than 10.00mL, less than 10.00mL, or exactly 10.00mL?

2a.) Explain your answer from question 1.

1bYour lab partner is using a 25.00 mL pipet for the first time. After he adjusts the liquid so the meniscus is at the calibration line, he squeezes the bulb (collapses the large bulb) to push all of the liquid out of the pipet.

1b.) Did your lab partner dispense more than 25.00 mL, less than 25.00 mL, or exactly 25.00 mL?

2b.) Explain your answer to question 1.

Answer 1

when there is an air bubble in the pipette which is filled up to the mark of calibration that is up to 10 ml here in this case some of the volume is also occupied by the air bubbles, so the total volume up to the mark of calibration is equals to the volume of the liquid plus the volume occupied by the air bubbles so the total volume of the liquid poured will be equal to total volume of calibration minus the volume occupied by the air bubbles. Hence volume of the liquid poured is less than 10 ml.

will be dispensing almost 25 ml of the liquid as there are no air bubbles and the bulb is squeezed hard o dispense al the liquid out of the pipette ,if th liquid sticking to the walls of the glass taken as negligible.