Evaluation of measurement uncertainty for volumetric glassware calibration from the variation of surface tension between liquid and glass

Abstract

Measurement uncertainties in calibration of volumetric glassware are from many sources for instance the weighting machine, environment, liquid temperature, position of meniscus. This paper described the uncertainty due to the cleanliness of volumetric glassware. With the less cleanliness, it will reduce the surface tension between the glass and the liquid. The less surface tension is the more contact angle and the less volume of meniscus. In the controversy the more contact angle is the more cleanliness, it will increase the surface tension between the glass and the liquid and the more volume of meniscus. In this case we found that the effect of deviation of contact angle will affect the uncertainty of the measurement of volume more that 50% of the overall measurement uncertainty. So the laboratory should pay more attention to the measurement uncertainty due to the variation of contact angle or surface tension between liquid and glass.