Why is the volume deviation between the graduated cylinder and the volumetric flask when looking down and looking up?
[ glass borosil volumetric flask,lab equipment glassware volumetric flask,volumetric flask with different size,250ml volumetric flasks with stoppers,volumetric flask capacity 250 ml]
When reading the measuring cylinder and the volumetric flask, if you look down or look up, the specific reasons for the deviation of the reading will be shown in the following figure:
1. Measuring cylinder reading:
When reading the measuring cylinder, the line of sight is to read the volume of the solution by staring at the lowest point in the center of the liquid surface.
When looking down, the line of sight is diagonally downward, and the intersection of the line of sight and the wall of the measuring cylinder is above the actual liquid level, which will cause the reading to be higher than the actual volume of the solution.
When looking up, the line of sight is diagonally upward, and the intersection of the line of sight and the wall of the measuring cylinder is below the actual liquid level, which will cause the reading to be lower than the actual volume of the solution.
2. Volumetric flask reading:
Generally, the volumetric flask has only one graduation line. When in use, people stare at the graduation line for constant volume.
When looking down, when the actual liquid level is lower than the scale line, human eyes feel that the liquid level has reached the position of the scale line at this time. The volume of the actual solution will be smaller, and the concentration of the prepared solution will be higher.
When looking up, when the actual liquid level exceeds the scale line, the human eye will feel that the liquid level has reached the position of the scale line at this time. The volume of the actual solution will be too large, and the concentration of the prepared solution will be too low.
Post time: Oct-15-2021
