Discussion Queationa: (to be answered on the report, not prior to lab) 1. Consid
ID: 573974 • Letter: D
Question
Discussion Queationa: (to be answered on the report, not prior to lab) 1. Consider how any individual determination of the density varies within a given piece of equipment. What does this indicate about the value of taking multiple measurements? How many measurements do you think would be "enough"? 2. Define precision and accuracy. Based on your experimental results, which thasware is most precise? Which is most accurate? Might operator skill affect the results? 3. Identify the piece of volumetric glassware best suited to the given use. a) Dispensing exactly 5.00 mL (and only 5.00 ml.) b) Holding water that will be used throughout the lab c) Measuring a volume to two decimal places d) Measuring a volume to one decimal place e) Making a solution at a specific concentration - - quantity of liquid (designated TD) and glassware designed to contain (designated TC) a specific volume of liquid? Give an example of each.Explanation / Answer
Density of any substance is the ratio of its mass to its volume.It is an intrinsic property,so its value is constant for any given sample of substance irrespespective of the sample size.
Its value varies according to the methods and types of instruments used for measuring mass and volume.If you use an analytical balance for measuring mass then it should be calibrated and the range of uncertainty determined.
Also for solids the lengths measurements must be done using calibrated callipers ,so that volume calculations using those measurements gives results that is accurate.
Accurate results are close to the accepted value and to get it multiple measurements must be taken giving close result,so that the result is precise as well.Both accuracy(closeness to the true value) and precision (closeness of repeated measurements ) are important in determining correct volume measurements.
The standard accepted accuracy ratio of multiple measurements is ten times (ten measurements must be close to accurate) however 3:1 ratio of accuracy is also generally acceptable