Name ______

Block ______

Comparing the Accuracy of Liquid Measuring Devices

Chemistry – Ms. Drommerhausen

Materials:

10 mL Pipette50 mL buret150 mL beaker

400 mL beaker100 mL graduated cylinderelectronic balance

25 mL graduated cylinderdistilled water100 mL beaker

Introduction:

Different liquid measuring apparatuses vary in the degree of accuracy which they measure the volume of a liquid. Five different apparatuses, a 10 mL pipette, a 25 mL graduated cylinder, a 100 mL graduated cylinder, a 150 mL beaker, a 100 mL beaker, and a 400 mL beaker will measure 10 mL portions of water. A 150 mL beaker will be used to receive the 10 mL of water being measured by each device. The precision of each instrument (assuming they are used correctly) will be determined by measuring the mass of the 10 mL portions. Since water at room temperature has a density of 1.00 g/mL, we can assume that the mass of 10 mL of water (if measured precisely) would have a mass of 10.0 g. By comparing the total mass of the water for each measuring device (10 mLportions) to the expected mass of 10.0 g, it is possible to determine which has the precision measuring 10 mL of water.

Procedure:

  1. Record all data in the data table provided
  2. Weigh a dry 150 mL beaker to the nearest .01 g on the electronic balance
  3. Using a 10 mL pipette, pipette 10 mL of water into the dry 150 mL beaker (use a pipette bulb when pipetting and touch the point of the pipette against the beaker to allow it to drain properly).
  1. Weigh the beaker and the water to the nearest 0.01 g and record the mass in the data table.
  1. Dry the 150 mL beaker, reweigh and repeat the procedure with the 50 mL buret, then a 25 mL graduated cylinder, a 100 mL graduated cylinder, a 100 mL beaker, and finally the 400 mL beaker
  2. Use the information provided in the calculation portion of your data sheet to determine the volume of water delivered by each instrument.
  1. When you are finished, dry all equipment and return it to its proper place.

Data Table

10 mL pipette 50 mL buret

Mass of the beaker + water ______g Mass of the beaker + water ______g

Mass of dry beaker (150 mL) ______g Mass of dry beaker (150 mL) ______g

Mass of water______g Mass of water ______g

25 mL graduated cylinder 100 mL graduated cylinder

Mass of the beaker + water ______g Mass of the beaker + water ______g

Mass of dry beaker (150 mL) ______g Mass of dry beaker (150 mL) ______g

Mass of water______g Mass of water ______g

400 mL beaker 100 mL beaker

Mass of the beaker + water ______g Mass of the beaker + water ______g

Mass of dry beaker (150 mL) ______g Mass of dry beaker (150 mL) ______g

Mass of water______g Mass of water ______g

  1. List the measuring devices from the most accurate (closest to 10.0 g) to the least accurate

a. ______b.______c. ______

d. ______e. ______f. ______

  1. Why is it difficult to accurately measure 10 mL of water with a 400 mL beaker
  1. Based upon the accepted value of 10.0 g of water being measure by each instrument, calculate the percent error for the most accurate and the least accurate instruments. Show your work with units and remember sig figs!!!!

a. Least accurate instrumentb. Most accurate instrument