Name: Date: Unit 1: Measuring the Earth - 2 Lab Hours Period: Lab: Density of Substances Introduction: You often hear statements like lead is heavier than water, or gold is the heaviest material on earth. These statements are not necessarily true, for if you had a barrel of water it would certainly be heavier than a shot of lead. What is implied, of course, is that if the volumes of the two substances were identical, then the lead would be heavier. This property of matter is called density. Problem: How can the density of a substance be measured? Objectives: After completing the lab, you should be able to: 1. Determine the volume of a solid and a liquid with reasonable accuracy. 2. Measure the mass of a solid and a liquid with reasonable accuracy. 3. Determine the density of a substance from a graph. 4. Describe the relationship between the mass and volume of different samples of the same substance. Procedure: 1. Determine the mass of a clean empty 10 ml graduated cylinder. 2. Using a pipette, measure 2 ml of alcohol into the graduate. 3. Determine the mass of the graduated cylinder plus the alcohol and then subtract the mass of the graduated cylinder to determine the mass of the alcohol. 4. Record the mass of 2 ml of alcohol in the appropriate box in data table A. 5. Using the formula for density, calculate the density of 2 ml of alcohol. Place your answer in the appropriate box in Data Table A. 6. Repeat steps 1-5 for each sample of alcohol listed in Data Table A. 7. Using the electronic balance, determine the mass of each sample of Aluminum. Place your answers in data table B. 8. Using a ruler, measure each side of each sample of aluminum. Calculate the volume of each sample using the formula, v = l x w x h. Place your answers in Data Table B. 9. Using the formula for density, calculate the density of each sample of aluminum. Place your answer in the appropriate box in Data Table B. 10. Construct a line graph of mass vs. volume of the alcohol samples. Label your line. 11. Construct a line graph of mass vs. volume of the aluminum samples. Label your line.
REPORT SHEET You are going to determine the density of four samples of alcohol and four samples of aluminum. Before you begin, answer the following questions. 1. Which substance will have a greater density? a. Why? 2. Fill in the data tables below by following steps 1-9 in the procedure. Data Table A: Density of 4 Samples of Alcohol Mass of empty 10 ml Graduated Cylinder: Sample Volume (ml) Mass (g) Density (g/ml) A B C D 2.0 ml 4.0 ml 6.0 ml 8.0 ml Data Table B: Density of 4 Samples of Aluminum Sample Volume (cm 3 ) Mass (g) Density (g/cm 3 ) A B C D
Mass (g) Density of Two Different Substances 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Volume (ml or cm 3 )
Analyzing the Graph 1. Which substance is more dense? 2. How does your graph show this? 3. Compare the densities of each sample of aluminum. 4. Compare the densities of each sample of alcohol. 5. Draw a line on the graph that accurately represents the density of water. 6. Where does the line for water fall in relation to the aluminum and alcohol? 7. Imagine that the water, alcohol and one piece of aluminum were dumped into the same cylinder. Assuming that the two liquids would not mix, draw and label the diagram to show how all three substances would separate in the cylinder.
DISCUSSION QUESTIONS: (Answer in complete sentences) 1. How did shape and size affect the density of the samples of aluminum? 2. If one of the aluminum samples were cut in half, how would the density of each half compare to the density of the original piece? 3. If you placed one of the samples of aluminum under tremendous pressure, what would happen to its density? 4. Of the three phases of matter (solid, liquid, gas), which has the greatest density for most substances? 5. If you had a bathtub full of Alcohol, how would density of the alcohol in the tub compare to the density of the 2 ml sample of alcohol? 6. If you increased the temperature of the alcohol, what would happen to its density? 7. Referring to your graph, what was the independent variable?
Mass (g) Mass (g) Mass (g) 8. Explain the relationship between the steepness of the slope and the density of the material. 9. Use the letters to place the graphs below in order of increasing density. Volume (ml) A Volume (ml) B Volume (ml) C CONCLUSION: Describe a procedure that could be used to determine the density of a gigantic boulder that was resting on your lawn. (Assume that the rock is uniform in composition and that it is too large to move).