Name_________________________________ Date_________________ Period____
Chemistry - Density Lab
Introduction:
All matter takes up space and has mass. The ratio of an object’s mass to its volume is an important physical property called density. Density is typically measured in grams per milliliter or grams per cubic centimeter.
This relationship is expressed in the formula for density:
Density is an intensive property. Intensive properties do not depend on the quantity of matter present. In other words, even if we possessed twice as much of a given material, the density would still be the same.
You will complete this lab with your lab partner(s). Record all data in the space provided
Part A – Density of a Solid
1.) Obtain one dice. Using an electronic balance, measure the mass of the dice in grams. Be sure your balance is zeroed before measuring mass. Don’t forget units!
Color _____________
Mass _____________
2.) Using a ruler, measure the volume of the dice. Measure each side to the nearest 0.1 cm so that your final unit for volume is cm
3
. Remember, the volume of a cube is calculated by the following formula:
Volume = Length x Width x Height
Length of Sides _____________ (1)
_____________ (2)
_____________ (3)
Volume ______________
3.) You now know the mass and volume of the dice. With this information, calculate the density of the dice, being sure to include units:
4.) The density of water is approximately 1.0g/mL. How does this compare to the density of your dice?
Does your dice float or sink in the water and does that make sense?
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Part B – Density of a Solid: Volume by Water Displacement
Sometimes is can be difficult to measure the volume of an odd shaped object with traditional geometry formulas. In science, we often measure the volume of these objects using a method called water displacement.
The volume of a specific amount of water is measured, the object is added, and the volume of the water and object is measured. The theory behind this is that the volume of water displaced is equal to the volume of the object.
1.) Mass approximately 5g of aluminum pellets. Record this value in the chart below.
2.) Obtain a 100mL graduated cylinder. Measure at least 50mL and no more than 90mL of water in the graduated cylinder. Record the exact volume of water in the table below.
3.) Gently slide the pellets into the graduated cylinder. Record the volume of the water and pellets combined.
4.) Calculate the volume in mL of the pellets by the water displaced in the space provided.
5.) Calculate the density of the pellets. Remember, density of solids is typically measured in g/cm
3
. This means you must convert mL to cm
3
. In addition to calculating the density, state the relationship between cm
3
and mL. Show your calculation below:
6.) Calculate the percent error for the density of aluminum. The actual density of aluminum is 2.7g/cm
3
.
Aluminum Pellet Data Table
Volume of Water
Volume of Water and Pellets
Volume of Pellets
Mass of Pellets
Density of Aluminum
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Part B – Density of a Liquid
1.) Mass a clean, dry 10mL graduated cylinder to the nearest 0.1g.
2.) Add 1.0mL of distilled water to a 10mL graduated cylinder. Make sure to read the volume accurately.
3.) Mass the graduated cylinder and its contents and record in the data table.
4.) Add another milliliter of distilled water to bring the volume of water in the cylinder to 2.0mL.
5.) Repeat steps of adding 1.0mL of distilled water and recording the mass until the total volume of distilled water in the cylinder is at 5.0mL.
6.) Repeat steps 2-5, using alcohol instead of distilled water. Dispose of alcohol in container provided by the teacher.
Distilled Water Data Chart
Mass of empty cylinder ________ g
1.0mL of Water
2.0mL of Water
Mass of Cylinder and Water Mass of Water
3.0mL of Water
4.0mL of Water
5.0mL of Water
Alcohol Data Chart
Mass of empty cylinder ________ g
Mass of Cylinder and
Alcohol
Mass of Alcohol
1.0mL of Alcohol
2.0mL of Alcohol
3.0mL of Alcohol
4.0mL of Alcohol
5.0mL of Alcohol
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Data Analysis:
1.) Create a line graph on the graph paper provided below. Plot the mass on the (y) axis and the volume on the (x) axis. Start both of the scales at (0,0). Plot the points for the volume and mass of water and alcohol on the same graph.
2.) Draw the best straight line through the data points for water and another straight line through the data points for alcohol. Both lines should intersect at (0,0).
3.) Determine the average density of water by calculating the slope of the line on the graph. Slope can be calculated by the following formula:
Slope = Rise
Run or (y
2
– y
1
)
(x
2
– x
1
)
Slope Calculations:
Water Alcohol
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Conclusions
1.) How does the mass of the distilled water compare to the mass of the alcohol?
2.) How does the volume of the distilled water compare to the volume of the alcohol?
3.) How does the density of the distilled water compare to the density of the alcohol? Does this surprise you based on the fact that density is an intensive property (Think: what if density were an extensive property)? Explain.
4.) The density of an unknown substance is graphed. The line has a very steep slope. What conclusion can be reached about the density of the substance?
5.) Were you close to the actual density values of water, alcohol, and aluminum? How close?
6.) If you had any percent error, speculate on the causes of such error.
7.) Describe a method to determine the density of an unknown, odd-shaped rock. Be specific about how you would obtain the volume.
8.) How can density be used to identify substances?
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