Regents Earth Science Name: Date: Lab # DENSITY of Solids and Liquids Introduction: Density is the term used to describe the relationship between the mass of an object and its volume. Under given conditions of temperature and pressure, the density of a material is constant. The density of any earth material can be determined by measuring its mass and volume and using the equation: Density = Mass Volume The density of fluids in either the liquid or gaseous state is very important when considering earth science topics such as ocean current flow, the turnover of lakes, wind patterns in the atmosphere and movement of the plastic asthenosphere. In this lab we will determine the density of three different liquids and then plot a graph to illustrate the differences in density. Objective: You will be able to calculate the densities of different materials and recognize that density is one of the most important properties of matter. 100 ml graduated cylinder Glycerol Water Alcohol Electronic Balance Triple beam balance Solid objects Ruler Calculator Procedures: Part A - Solids 1. Measure the mass of each object using a triple beam balance. Your answer should be recorded in grams (g) to the nearest tenth (0.1) on Report Sheet 1. 2. Find the volume of each object using a metric ruler and the equation in the above or by using the water displacement method. Your answer will be in cm 3 or ml. 3. Calculate the density of each object by dividing the volume into the mass. 4. Record your data on Report Sheet 1. Density Solids and Fluids 9/12/2011 1
REPORT SHEET 1 Material Mass (g) Volume (cm 3 ) Density (g/cm 3 ) 1 2 3 4 Procedure: Part B: Liquids 1. Determine the mass of a clean, dry graduated cylinder on the electronic balance. Record its mass below. This will be used in future calculations. 2. Accurately measure 10 ml of water into the graduated cylinder. Record the mass of the cylinder and 10 ml of water in the data table. 3. Add successive amounts of 5 ml each into the graduate to equal 15 ml, 20 ml, 25 ml and 30 ml. Mass the graduate and each amount of water and record it in the data table. 4. Repeat procedures 2 & 3 with the alcohol. Be sure to record all measurements. 5. Repeat procedures 2 & 3 with the glycerol. Record all measurements. Density Solids and Fluids 9/12/2011 2
REPORT SHEET 2 Mass of Empty, DRY cylinder = Volume of Liquid (ml) Mass Cylinder + liquid (g) Mass of Liquid (g) Density of Liquid (D= m/v) Average Density (g/ml) 10 ml water 15 ml water 20 ml water 25 ml water 30 ml water 10 ml alcohol 15 ml alcohol 20 ml alcohol 25 ml alcohol 30 ml alcohol 10 ml glycerol 15 ml glycerol 20 ml glycerol 25 ml glycerol 30 ml glycerol Graphing: 1. Subtract the mass of the clean, dry graduated cylinder from each total to determine the mass of the liquid ALONE. 2. Using this value for the mass of the liquid and the volume from the graduated cylinder calculate the density of each liquid and find the average. 3. On the graph paper provided, place VOLUME on the horizontal (X) axis and MASS on the vertical (Y) axis. Label each axis and include units! Density Solids and Fluids 9/12/2011 3
Density of Liquids (Mass vs. Volume) Density Solids and Fluids 9/12/2011 4
Questions: 1. If one of the original solid materials in this lab were cut in half, the density of each half would be A) less than the original sample B) the same as the original sample C) greater than the original sample 2. In which phase (state) do most Earth materials have their greatest density? A) Gas B) Solid C) Liquid 3. What would be the expected change in density as the temperature of a material increases? Hint: think about a hot air balloon 4. What would be the expected change in density of a material as pressure increases? Hint: think about a propane or SCUBA tank.. 5. Water is an unusual earth material because it is most dense in which phase? 6. What is the density of a rock which has a mass of 35 grams and a volume of 7.0 cubic centimeters? A) 42 g/cm3 B) 0.20 g/cm3 C) 28 g/cm3 D) 5.0 g/cm3 7. Which liquid in this experiment has the least density? What was its average calculated density? Density Solids and Fluids 9/12/2011 5
8. If all three (3) liquids were poured into one (1) container, how would the mixture settle? Draw a picture of what it would look like; be sure to label each liquid. 10. The diagram below shows a glass jar containing a clear liquid and a floating rock. Which conclusion about the relative density of the rock and the liquid is true? A) The rock and the liquid have the same density. B) The rock is less dense than the liquid. C) The rock is more dense than the liquid. Density Solids and Fluids 9/12/2011 6
11. The diagram below shows equal masses of four different earth materials at different temperatures. Which material has the greatest density? A) granite B) iron C) dry air D) water 12. A student calculates the densities of five different pieces of aluminum, each having a different volume. Which graph best represents this relationship? Density Solids and Fluids 9/12/2011 7