Precision, Accuracy, and Density Measurements
Abstract- Expirement 1: Precision, Accuracy, and Density Measurements This experience is intended to introduce the proper use of the most used laboratory equipments and glasswear that is come upon in the lab. As well, to determine the mass, volume and density of water by using various types of measuring glasswear, such as beakers, graduated cylinder, pipet, etc… The measurement of the density of water will determine the precision and accuracy of these measuring glasswear.
Also, there will be a density calibration graph, used to determine an unknown value, prepared using NaCl solutions of known concentration prepared in lab to determine the concentration of an “unknown” NaCl solution. (General chemistry 1, Lab Manual, p. 13) For results, the most accurate and precise glasswear will be determined between the different types of measuring glasswear used. Room temperature tap water was filled in different types of glasswear with different measurement of tap water, were the volume was recorded.
For the first part, the glasswear were weighted when dry, followed by being filled to determine the mass with a certain amount of tap water. This part determined the precision and accuracy of density measurements. For the second part, a NaCl solution of a given solution was to be prepared and had to measured its density. This part gave results to build a calibration graph. In part 1, it was determined that the graduated cylinder is the most accurate and precise, as the average density, 0. 87g/mol, was very close to the accepted value, 0. 9977045g/mol. The percentage of error in the table 1. 1 (graduated cylinder) was very low, with 1. 10% compared to 15. 8% in table 1. 2 (pipet) and 1. 92% in table 1. 3 ( buret). A reason for which the graduated cylinder was the most accurate and precise could be for the following: one was capable of measuring the amount of tap water at an eye level, as for the pipet it was too high and a miscalculation could have happened seeing that one has to calculate a beginning and an end.
A percentage of error occurs from miscalculations, from adding 0. 01 ml more water than should be put or something as simple as spilling some tap water from a glasswear to another. This experiment allows one to learn the usage of the different glasswear. It determines which of these glasswear is the most accurate and precise, and was found that the graduated cylinder gave the best results. To avoid percentage error, one should be more careful and double check the calculations.