Density Lab



The Density of Earth Materials

Objectives:

1. To measure the mass and volume of several objects.

2. To compute and compare the density of these objects.

Density measures the amount of earth material (mass) in a given space (volume). D = M/V

Density = Mass (g) divided by volume (ml) or (cm3)

Materials: 1 cube 1 rectangle metric ruler unknown mineral 100 ml graduated cylinder balance

Density of Regular Solids

Part A.

1. Determine and record the mass of the cube to the nearest tenth of a gram.

2. Using the metric ruler, measure and record the dimensions of the cube.

3. Using the formula, (length x width x height), compute and record the volume of the cube.

4. Use the mass and volume to compute the density. Record in Table 1. Include UNITS!

Part B.

1. Repeat the same procedure using the rectangle formula (l x w x h). Include UNITS!

2. Record results in Table 1.

Table 1 Density of a Regular Solid

|OBJECT |MASS |LENGTH (cm) |WIDTH |HEIGHT |VOLUME |DENSITY |

| |(g) | |(cm) |(cm) |(cm3 ) | |

|CUBE | | | | | | |

|RECTANGLE | | | | | | |

Finding the Density of an Irregular Solid

Part C.

1. Pour 50 ml of water into a 100 ml graduated cylinder. Read and record the volume.

2. Use the balance to determine and record the mass of the graduated cylinder plus water.

3. Carefully slide the mineral into the graduated cylinder. Tilt the cylinder so the mineral does not splash.

4. Read and record the new volume.

5. Subtract the original volume from the new volume. Record this number as the volume of the mineral.

6. Use the balance to find the mass of the cylinder plus water plus the mineral.

7. Subtract your two mass numbers and this will give you the mass of the mineral.

8. Use the density formula to determine the density of the mineral.

Table 2 Density of an Irregular Solid

|OBJECT |STEP 1 |STEP 2 MASS OF |STEP 4 VOLUME OF |STEP 5 VOLUME OF |STEP 6 MASS OF |STEP 7 MASS OF |STEP 8 DENSITY OF|

| |VOLUME WATER |CYLINDER AND |WATER PLUS |MINERAL |CYLINDER, WATER, |MINERAL |MINERAL |

| |(ml) |WATER |MINERAL |(ml) |AND MINERAL |(g) |(g/ml) |

| | |(g) |(ml) | |(g) | | |

| | | | | | | | |

| | | | | | | | |

Determination of Density

1. Measure the mass of the sample with a balance and record it as mass in grams.

2. Measure the height (h) and diameter (d) of the sample. To find the radius, divide the diameter by 2.

3. Calculate the volume of the sample by using this formula:

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4. Use the water displacement method to determine the volume of the sample. Record each one in the table.

5. Determine the density of the sample using both calculated volumes.

***MAKE SURE YOU RECORD THE DENSITY USING THE CORRECT UNITS!!!***

|SAMPLE |MASS |DISPLACEMENT VOLUME |**DENSITY |FORMULA VOLUME |**DENSITY |

|ALUMINUM | | | | | |

|BRASS | | | | | |

|STEEL | | | | | |

|COPPER | | | | | |

Graph your results using the displacement volume (ml) (x-axis) and measured mass (g) (y-axis) for each sample.

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6. On your graph, draw and label a line for a material with a density of 1.0 g/ml. Where is this line relative to the line for the cylinders? Does this line give you a clue as to whether the cylinders will sink or float?

7. If you cut the copper sample in half, what would be the density of each piece? Why? Plot this new point (half of the mass and half of the volume) on the graph.

ACADEMIC ONLY

Part D. Conclusion questions.

1. What would be the volume of a rectangular solid with the dimensions: 8 cm x 10 cm x 2 cm? What would the density be if the mass is 125.5 grams?

2. If you had a metal cylinder, what method would you use to determine its volume?

3. What is the density of water? (Do a computer/book search if needed).

4. What will happen to objects that have a density less than water? Greater than water?

PHYSICAL PROPERTIES OF MATTER

Change the italicized word in each statement to make it correct.

10. The size of an object determines whether it will float in water.

11. Orange juice and milk are both solids.

12. Stars are made up of matter in the gaseous state.

13. An object’s density is equal to its mass divided by its length.

14. Matter with atoms in a fixed position in relation to one another is in the liquid state.

15. Density and state of matter are chemical properties.

16. Hydrogen is the only substance that occurs naturally on Earth as a gas, a liquid, and a solid.

17. The physical properties of a liquid do not change when it becomes a gas.

18. Liquids fill their entire container regardless of the container’s size or shape.

19. On Earth the solid state of matter is least common.

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Volume vs. Mass of Ag

Observe the following graph and answer the questions.

5. The line shown on the graph represents the density of what element?

6. If the mass of the element is 72 grams, what is the volume of the element?

7. If the volume of the element is 2 ml, what can we assume is the mass?

8. Complete this sentence: According to the graph, as the mass of an element increases the volume ______________________.

9. Plot the following points on the graph for element B.

Mass = 10g Volume = 2 ml

Mass = 40g Volume = 8 ml

If the element shown in the graph and element B were dropped in a solution with a density of

7 g/ml, which one would sink?

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