This document discusses measuring liquid volumes precisely in a laboratory setting. It describes different equipment used for measuring liquids based on the required volume, accuracy, and whether repetitive measurements are needed. Pasteur pipettes, conical flasks, beakers, measuring cylinders, volumetric flasks, burettes, glass pipettes, syringes, and microsyringes are all described in terms of their best volume ranges and accuracy. Special considerations are discussed for viscous, volatile, or foaming liquids. Proper techniques are demonstrated for using pipettes, conical flasks, and beakers. Volumetric flasks, burettes, pipettes, microsyringes are highlighted as providing reliable volume measurements.

1. WORKING WITH LIQUIDS IN
LABORATORY
Author: Mr Lam

2.  A lot of chemicals in the laboratory is in liquid
form, e.g. acid, water and ethanol.
 We need to know or control the volume of the
liquids we used.
 Therefore, we need to measure the liquid
volume precisely. This powerpoint is to show
the general procedures in handling liquids

3. Measuring volume
 The equipment you should choose to
measure out liquids depends on:
1. Volume to be dispensed
2. The accuracy requirement
3. The number of times the job must be
repeated.

4. Examplesof measuringequipment

6. Method Best volume range Accuracy
Usefulness for
repetitive
measurment
Pasteur Pipette 1.5mL Low Convenient
Conical Flask/Beaker 25-5000mL Very low
Convenient
Measuring cylinder 5-2000mL Medium
Convenient
Volumetric flask 5-2000mL High
Convenient
Burette 1-100mL High
Convenient
Glass Pipette 1-100mL High
Convenient
Syringe 0.5-20μL Medium Convenient
Microsyringe 0.5-50μL High Convenient
Weighing
Any (depends on
accuracy of
balance)
Very High Inconvenient

7. Otherconsiderations
Somespecialliquidsmaycauseproblems
1. High-viscosity liquids are difficult to dispense:
need more time for the liquid to transfer
(Honey)
2. Organic solvents may evaporate rapidly,
making measurements inaccurate: work quickly,
seal containers quickly (acetone, ethanol)
3. Solutions prone to frothing are difficult to
measure and dispense: avoid forming bubbles,
do not transfer quickly (soap solution)

8. HowtoholdaPasteurpipette

9. Differenttypesofpipettes
 Graduated pipette reading
from zero to shoulder
 Graduated pipette, reading
from maximum to tip
 Bulb (volumetric) pipette

10. How to fit pipette filler

11. ConicalFlasksandBeakers
 The markings on the these containers are not
accurate. They should only be used for
measuring volume of solutions, liquids where
accuracy is unimportant.
beaker
Conical
Flask

12. Reliableequipmentformeasuringvolume
Burette Pipette
Volumetric flask
Microsyringe