The study of Chemistry involves not only the observation of changes in matter, but also the measurement of these changes. In fact, most chemical principles cannot be fully understood without obtaining and analyzing some quantitative data. The techniques of data collection, data analysis, and measurement are a very important part of chemistry.

A useful way of comparing two substances is to compare their densities. By carefully measuring the masses of equal volumes of two substances, their densities can be calculated by simply dividing their masses by their volumes.
                     mass
    Density =  ---------
                     volume

PURPOSE:
In this experiment you will make a number of measurements and you will use these measurements to determine a physical property: density.

PROCEDURE:

A. DENSITY OF WATER
1. Tare the mass of a 100 ml graduated cylinder.
2. Use the balance to add exactly 50.00 g of water to the graduated cylinder.
3. Read the bottom of the meniscus and record the volume to the nearest 0.5 ml.
 

B. DENSITY OF A COMMON LIQUID
1. Tare the mass of a 10 ml graduated cylinder.
2. Fill the graduated cylinder to about the 9 ml mark with the liquid and read the volume to the nearest 0.2 ml.
3. Record the mass.
4. Record the calculated densities for all other liquids throughout the room.

C. DENSITY OF A SOLID
1. Obtain four different samples of copper. (penny, wire, shot, turnings)  Record each of the masses.
2. Fill a 50 ml graduated cylinder about half way with tap water. Read and record the volume of water to the nearest 0.5 ml.
3. Carefully immerse the solid in the water in the cylinder and record the new volume to the nearest 0.5 ml.
4. Empty the contents of the graduated cylinder into the sink but retain the solid for future experiments. Dry the samples on paper towels.

DATA TABLE  (remember to include units)
Part A:
mass of water                                  ___50.00 g____
volume of water                               _____________

Part B:
liquid                                                 _____________
mass of liquid                                    _____________
volume of liquid                                 _____________

Part C:
mass of copper penny                       _____________
mass of copper wire                          _____________
mass of copper shot                          _____________
mass of copper turnings                    _____________
volume of grad. cyl. without penny    _____________
volume of grad. cyl with penny          _____________
volume of grad. cyl without wire        _____________
volume of grad. cyl with wire             _____________
volume of grad. cyl without shot        _____________
volume of grad. cyl with shot             _____________
volume of grad. cyl without turnings  _____________
volume of grad. cyl with turnings       _____________

CALCULATIONS and QUESTIONS
1. Calculate the density of water using the data from Part A. Show all work and be sure to include the proper units.

2. Calculate the density of your liquid using the data from Part B. Show all work and be sure to include units.

3. Using the classroom data, list the densities of all the liquids in increasing order.

4. Construct a best-line fit graph using the mass and volume of your copper samples using the data collected in Part C.  (Mass on y-axis and volume on x-axis) Be sure to label all parts of your graph. Calculate the density of copper based on your graph. Show all work.

5. Calculate the density of the copper penny, wire, shot and turnings bases on your mass and volume measurements in Part C. How do they compare to the density calculated from the graph? Which do you think is more accurate?

6. Why wouldn’t water displacement always be an effective method for determining volume?