ABSTRACT The objectives of the experiment include illustration of the use of analytical balance, studying the precision of weighing made with it and evaluating the common error encountered in weighing. Weight of the vial, the cap, vial with cap and the vial that was induced with the factors affecting the sensitivity of the balance (e.g. moisture) were determined. As seen, there were significant differences on the weights though there were some errors observed. Expected results were not seen because of certain influences that somehow affected the precision and accuracy in weighing. All in all, the objectives of the study were met.
INTRODUCTION The analytical balance is a fundamental measuring device for all types of quantitative work in analytical chemistry. It is designed for great precision in quantitative chemical analysis. It yields readability to four decimal places to the right of the decimal point (up to .0001 g). It is extremely sensitive and requires a draft-free location on a solid, flat surface that is free from vibrations. Analytical balance is used for samples up to about 320 g. The importance of the study relies on the proper handling and weighing of the balance to minimize errors and attain the maximum precision and accuracy in weighing a certain sample through the analytical balance.
The experiment aims to illustrate the use of analytical balance, study the precision of weighing made with it and evaluate the common error encountered in weighing.
RESULTS
Table 1: Weight of Vial and Cap
Weight of dry vial:
(Step 1) 20.2981 g
(Step 4)
20.2978 g
(Step 5)
20.2977 g
(Step 6)
20.2975 g
(Step 7)
20.2977g
Weight of cap:
(Step 2)
2.0041 g
Weight of dry vial and cap (Step 3) 22.3020 g Table 2: Differences in Mass
Bet. The total mass in 1 &2 and that observed in 3
0.0002 g
Bet. 1 & 4
0.0003 g
Bet. 1 & 5
0.0003 g
Bet. 1 & 6
0.0006 g
Bet. 1 & 7
Cited: Lab Manager.com, April 7, 2009