A Graduated Cylinder is one of the most common instruments used in the lab to obtain the volume measurements of liquids.
It is also known as mixing or measuring cylinderIts shape is narrowing cylindricalThe lines that are marked on the cylinder signify the value of the volume that has been measured through observing the ends of the liquid droplets on the cylinder.
- Check the Marks on the Cylinder
The graduated cylinder has various capacities; each has its own specific graduation marks on the outer surface. Though there is a general capacity and that is 5ml to 500 ml. So, first, it must be known that each graduation mark corresponds to how much of the volume value. Ensure that the graduation cylinder that is purchased is from a verified seller and check the surface for any defects that might be prevalent. The most common ones are cracks which appear at the tip ends and do not carry measurements if there are any discrepancies on the surface. Further, also ensure that there are the starting and the ending graduation on the cylinder. And scan briefly to ensure that equal spacing exists between them. A beaker, flask or conical is employed as a graduated cylinder to measure the liquid volume, let’s take water here. However, their sign of volume is an approximation, therefore, to get a result as higher accuracy a marked cylinder would be more appropriate.
- Graduated cylinder n deg 1- The volume between two graduations corresponds to 10mL.
- Graduated cylinder n deg 2- The volume between two graduations corresponds to 2mL.
- Graduated Cylinder n deg 3- The volume between two graduations corresponds to 1mL.
- Undertake the Measurements
Now, in order to begin the measurements, the graduation marks that are closest to the other end of the cylinder that is the free surface of that particular liquid must be known or determined. Then, the observer must watch the marking from the same level as the graduation in order to avoid the parallax error. Not above, not below, at the exact level as a free surface.
- Do the Math
Using the earlier information and some Math, the volume can now be calculated. For example:
If the liquid is one mark below 100, then, we can calculate the volume as follows:
- 100- 10= 90; Volume= 90 ML
If the liquid is two marks above 5, then, the calculation will be as follows:
- 5+2=7; Volume= 7 ML
If the liquid is one mark above 100, then, the calculation would be as follows:
- 100+10=110; Volume= 110 ML
Note that, due to the capillary effect of the water, the droplets might get attached to the walls of the cylinder in which the measurement is being taken. This process might not be widely seen in the case of wide cylinders but are very prevalent in narrow cylinders. In order to correctly measure the volume, one must make sure that the lower surface of the liquid droplet is taken as the reference and this, in other words, is also known as the lower meniscus.