DENSITY of SOLIDS and LIQUIDS LAB
NAME:
DENSITY of SOLIDS and LIQUIDS LAB
PRELAB
Read the lab and answer the following questions on a separate sheet of paper. Use complete sentences or show mathematical calculations showing work, units, and significant figures.
1. Find the equations that you would use to calculate the volume of a cube, a rectangular solid, a cylinder, and a sphere (hint-consult your planner or math text).
2. True or False – A ton of steel will have a larger density than 1 steel nail.
3. Find the mass of a brass sample if it occupies a volume of 10.0 cm3 and the average density of brass is 8.0 g/ cm3.
4. Read the volume on each of the graduated cylinder pictures shown in the background section and then determine the volume of the object that was submerged in the cylinder to make the water level rise. Report your answer to the proper number of decimal places/ significant figures.
5. Use the terms inversely or directly to complete the following: Mass and density are ______proportional. Volume and density are ______proportional.
OBJECTIVE
1. To find the density of a metal cube, a rectangular solid, and a liquid sample and to use the density to identify the substance.
2. To use water displacement to determine the volume of an irregular shaped object and to use that volume to calculate density.
3. To graphically analyze mass and volume to determine the density of a sample of brass.
4. To use density to determine the % composition of pennies.
5. To determine the thickness of a piece of aluminum metal.
6. To analyze data using average, average deviation, and percent error calculations.
BACKGROUND
Matter can be described qualitatively through observation of intensive or extensive physical or chemical properties. This lab will explore the extensive properties of mass and volume and their relationship to the intensive property, density. Recall that mass is a measure of how much matter is in a substance. The standard unit for measuring mass is the kilogram, however, our lab balances are calibrated using grams. Volume is a measurement of the amount of space occupied by a sample of matter. Volume is measured in units of cm3 or ml. When mass is divided by volume, the result is the density of the substance.
DENISTY = MASS
VOLUME
The resulting units of density are g/cm3 or g/ml. The obtained density value may be used to identify an unknown sample by comparing it to a chart of known (theoretical) density values. You could find such a chart in your textbook or in the CRC Handbook of Chemistry and Physics. Possible identities of substances used in this lab include: aluminum, brass, copper, cadmium, tin, bronze, lead, steel, zinc, ethanol, ethylene glycol, corn oil, glycerol, or water.
This lab will employ two techniques to determine the volume of objects. One technique involves measurements of the dimensions of the object and using mathematical relationships to find the volume of regular shaped objects. This method assumes that the object is solid and free of air space. If, however, the solid is irregularly shaped or contains air space between [articles, it is necessary to perform water displacement to find the volume. This method begins with a known volume of water in a graduated cylinder. Then the object is placed into the water and the new volume is recorded. The difference in the recorded water volumes must equal the volume of the object submerged in the water. In order for water displacement to work, the object must be completely submerged in the water and must not be soluble or able to chemically react with the water.
Here is a sample graduated cylinder before and after the object is submerged. The volume of the water should be read to 1 decimal place (1 digit beyond the markings on the cylinder). The last digit is an estimated digit which adds some amount of uncertainty to the volume reading. This uncertainty may lead to errors in your density calculations.
Luckily, determining the mass of each sample is quite easy. You will use the electronic balance and record the masses to the second decimal place.
MATERIALS
NAME:
Electronic balance
Weighing dish
Calipers
Ruler
100 ml graduated cylinder (plastic, so that it does not shatter when the sample is introduced)
Pipette(s)
Cubic metal samples
Rectangular solid samples
Irregular shaped solids samples
Pennies
Aluminum foil
Unknown liquid samples
NAME:
PROCEDURE
The following parts may be completed in any order.
PART I: CUBIC SOLIDS
1. Obtain a metal cube and make qualitative observations.
2. Find the mass of your cube.
3. Determine the average length of a side of the cube.
4. Return the cube to its storage box.
5. Perform calculations of volume, density, and percent error. Identify the metal sample and determine the % error of your result.
PART II: RECTANGULAR SOLIDS
1. Obtain a rectangular solid and record its ID number as well as qualitative observations.
2. Find the mass of the solid.
3. Determine the length, width, and height of the solid.
4. Return the rectangular solid to its storage box.
5. Perform calculations of volume, density, and percent error. Identify the rectangular solid sample and determine the % error of your result.
PART III: DENSITY of BRASS
1. Obtain five brass cylinders and record qualitative observations.
2. Record the mass of each cylinder.
3. Record the length and diameter of each cylinder.
4. Return the cylinders to their storage box.
5. Perform calculations to determine the volume of each.
6. Create a graph of mass vs. volume for the five cylinders. Include two titles, axes labels and units, data points connected by a line and show a slope calculation after determine the line of best fit through the points. The slope represents the density of brass.
7. Calculate % error.
8. Given the density of copper and zinc, determine the % of each element combined to make the alloy, brass.
PART IV: IRREGULAR SHAPED OBJECT
1. Obtain and irregular shaped metal object and record qualitative observations.
2. Record the mass of the object.
3. Determine the volume of the object through water displacement. Fill a 100 ml graduated cylinder to approximately the 50 ml mark. Record the exact volume to 1 decimal place. Carefully place the metal sample into the cylinder and record the new volume of the water.
4. Dry your metal sample and return it to its storage box.
5. Repeat 1-4 with another sample.
6. Share your data with another group that used the same metal samples.
7. Perform calculations of volume, density, percent error, average deviation, and a precision check. Identify the irregular solid sample and determine the % error of your result.
PART V: % COMPOSITION of PENNIES
1. Obtain 10 pennies making sure that they are all post 1982.
2. Record the mass of the 10 pennies. Determine the average mass of one penny.
3. Use water displacement to find the volume of 10 pennies. Determine the average volume of one penny.
4. Calculate the density of the pennies using the mass of all 10/ volume of all 10 and also using the average mass of 1 penny/ average volume of 1 penny.
5. Determine the % of the penny (post 1982) that is actually copper given the fact that the inner core of the penny is zinc.
PART VI: LIQUID DENSITIES
1. Select one of the four mystery liquids to identify. Record its letter and qualitative observations.
2. Weigh three empty pipets. Find the average mass of an empty pipet.
3. Use the pipet in the container of liquid and draw up 1.0 ml of solution to the line right below the bulb of the pipet. Quickly release the pressure on the bulb and invert the pipet so that the liquid flows into the bulb end. Carefully clean the exterior of the pipet. Find the mass of the pipet and liquid by placing the filled pipet in a weighing dish (that has been tared) on the electronic balance. Repeat finding the mass three times with the same liquid.
4. Calculate the average mass of the liquid, the average density, compare the density to the theoretical values and determine the identity of the mystery liquid. Report your percent error, average deviation, and precision check.
PART VII: THICKNESS of ALUMINUM
1. Obtain a piece of aluminum foil.
2. Write a procedure that will allow you to determine the thickness of the piece of foil.
3. Carry out the procedure and report your results in a data table that you design.
4. Consider averaging your data with other groups to validate your results.
DATA
PART I: CUBIC SOLIDS
QL observations of the metal:Calculation
(show only when necessary) / Value and Unit
Mass of cube
Length of side
Volume of cube
Density (experimental)
Possible identity of metal
Theoretical density
% error
PART II: RECTANGULAR SOLIDS
ID #QL observations of the rectangular solid:
Calculation
(show only when necessary) / Value and Unit
Mass of solid
Length
Width
Height
Volume of rectangular solid
Density (experimental)
Possible identity of solid
Theoretical density
% error
PART III: DENSITY of BRASS
QL observations of the cylinders:Cylinder # / mass / length / radius / volume
1
2
3
4
5
Attach a full sheet graph of mass vs. volume data.
Density of brass from graph: / Slope calculation:
% error (given average theoretical density of 8.00 g/ml)
PART IV: IRREGULAR SHAPED OBJECT
QL observations of the metal:Calculation
(show only when necessary) / Value and Unit
Mass of irregular object
Final volume of water after object is submerged
Initial volume of water
Total volume of water displaced = volume of the irregular object
Density (experimental)
Possible identity of metal
Theoretical density
Density data from other groups:
Initial each data set
Calculation (show all work) / Value and unit
Average density:
% error
Average deviation
Precision check
PART V: % COMPOSITION of PENNIES
Calculation(only show when necessary) / Value and unit
Mass of 10 pennies
Volume of 10 pennies
Density using mass and volume of 10 penny data
Average mass of 1 penny
Average volume of 1 penny
Density using average mass and volume of 1 penny
Theoretical density of a post 1982 penny
% of copper and % zinc in the penny
% error of penny density
PART VI: LIQUID DENSITIES
Liquid letter ID:QL observations of liquid sample:
Calculations (show when necessary) / Value and unit
Mass of empty pipet / 1. / 2. / 3.
Average mass of empty pipet
Mass of pipet and liquid
Mass of liquid
Volume of liquid inside pipet
Density of liquid
Average density of liquid
Possible identity of liquid
Theoretical density of liquid
Percent error
Average deviation
Precision check
PART VII: THICKNESS of ALUMINUM
You design the data table. Graph paper may be used to help keep it neat.
POST LAB QUESTIONS
1. A cylinder of lead has a radius of 2.6 cm and a height of 12 cm. What is the mass of this piece of lead?
2. A cube of aluminum has a mass of 25.50 grams, determine the dimensions of the cube.
3. A rectangular block has dimensions: 4.5 cm x 1.7 cm x 7.8 cm. The mass of the block is 312 grams. Based upon this, will this block float or sink in water?
4. A cylindrical tin can has a height of 22.00 cm, an external radius of 5.00 cm and an external radius of 4.99 cm. Given the density of tin = 2.8 g/cm3, determine the mass of the empty tin can. If the can is filled with water, calculate the mass that would appear when the filled can is placed on the electronic balance.
5. An alloy of bronze was made by combining 88 % copper and the rest is composed of tin. Determine the density of the bronze sample using a weighted average.
6. Would it be possible to calculate the volume of a sample of calcium metal using water displacement? Explain.
7. Why did the pennies all have to be post 1982? Would the density have been higher or lower given pre-1982 pennies?
8. Given the % of copper that you found in the post 1982 pennies and given your total mass of pennies, what is the true value of the copper in the pennies? (hint – find the current scrap value of copper). Would increasing the amount of zinc in the core help reduce the cost of the penny? Research and explain.
9. Why didn’t we determine the density of any gases in our lab? When reporting density of gases, what is the most appropriate unit?
10. The density of petroleum oil is less than the density of sea water. Explain how this fact will help in an oil spill cleanup.