Density of Liquids Lab

Purpose: To learn how to determine the density of a liquid

Materials:

water 10 mL graduated cylinder balance

Procedure: Part 1

1.  Using the balance, determine the mass of a CLEAN, DRY 10 mL graduated cylinder. Record in Data Table 1-1.

2.  Add some water to the graduated cylinder and record the volume as accurately as possible.

3.  Determine the mass of the graduated cylinder and water. Make sure the outside of the cylinder is dry. Record in Data Table 1-1.

4.  Repeat procedure #2 and #3 three more times using different volumes of water each time.

5.  Calculate the density of the water and record. Determine the average density and compare this to the accepted density of water.

6.  GRAPH 1-1: Volume of water (x) vs. Mass of water (y). Draw a BEST FIT LINE.

Trial / Mass of Graduated Cylinder / Volume of Water / Mass of Cylinder + Water / Mass of Water / Density of Water
1
2
3
4
Average Density

Data Analysis:

1.  What is the density of water according to the slope of your graph?

2.  How does the calculated value compare to the value obtained from the graph? Describe at least two reasons for why there may be differences in the values.

3.  Calculate your percent error for the density of water. (SHOW YOUR WORK)

% error = \ Accepted Value – Experimental Value \ x 100

Accepted Value

Procedure: Part 2

1.  Select an unknown liquid sample and determine its density. RECORD the number of the unknown.

2.  Design your own experiment to determine the density of your unknown and write a complete laboratory report (Part 2 only) for this procedure. Include safety precautions and a graph of the results. Use both slope of the line on the graph and your calculations to determine the final density of your unknown. Each partner pair should have a different unknown. Always treat unknowns as if they are hazardous substances.

3.  At the end of the experiment, all the equipment should be clean, dry and put away ready for the next lab experiment. Return all other equipment and the unknown solutions to the designated areas. Wash your hands and clean up your laboratory area before leaving the classroom.

Conclusion:

1.  What value of a measurement must be available if the accuracy of a measurement is to be determined?

2.  What are the possible sources of experimental error in this experiment? (3 errors minimum)

3.  David and Jill determined the density of a liquid three different times. The values they determined were 2.79 g/mL, 2.77 g/mL, and 2.81 g/mL. The accepted value is known to be 2.39 g/mL.

a.  Are the values, that David and Jill determined, precise? Explain.

b.  Are the values accurate? Explain.

c.  Calculate the percent error (Show your work)