SCIENCE 08 CHEMISTRY Notebook Page E
EXPERIMENT # 4
SEPARATION OF MIXTURES
PROBLEM:
1. To separate a mixture containing gravel, sand, salt, and iron into its component parts.
2. To recognize and classify mixtures as mechanical mixtures, suspensions, and solutions.
HYPOTHESIS:
It will be possible to separate the gravel from the mixture by , the iron
by , the sand by , and the salt by .
The sum of the masses of all the components will the mass of the original mixture
within a reasonable experimental error of ± %.
APPARATUS:
4 beakers labelled uniquely "gravel", "mixture", "salt", or "iron".
plastic petri dishes 150 mL beakers ring stand funnel
centogram balance test tube rack stirring rod filter paper
bar magnet heat lamp ring clamp seive
MATERIALS: A mixture of gravel, sand, salt, and iron provided by your instructor.
You may find the following properties of these materials useful:
GRAVEL: light brown, hard, large pieces, not soluble in water, extremely high melting and boiling
point , opaque, not magnetic.
SAND: white, hard, fine grains, not soluble in water, extremely high melting and boiling point,
opaque, not magnetic.
SALT: white, hard, fine grains, very soluble in water, high melting and boiling point, opaque, not
magnetic.
IRON: black, shiny, fine grains, not soluble in water, very high melting and boiling point,
opaque, magnetic.
WATER: colourless, liquid, translucent, melting point 0 ¡C, boiling point 100 ¡C, not magnetic.
PROCEDURE:
1. Devise a scheme for separating the sand, salt, iron, gravel mixture; complete the flow chart on
Diagram I provided, and have it approved by your instructor.
2. Empty the contents of the beaker labelled "mixture" onto a singly folded clean piece of scrap paper.
Clean, dry, and weigh all four beakers. Record the empty beaker weights in Table I.
3. Using the techniques indicated in your flow chart separate each component of the mixture and
transfer it into the appropriately labelled beaker. At each stage return unseparated components to
the beaker labelled "Mixture".
4. Reweigh each beaker including its appropriate separated contents and enter the results in Table I.
5. Provide your instructor with the four separated contents in their appropriate beakers for
inspection and evaluation.
EXPERIMENT #4: SEPARATION OF MIXTURES Page 2 Notebook Page E
DIAGRAM:
Draw a properly set up and labelled diagram of your filtering apparatus. The proper format for
scientific diagrams is summarized on Page A8 of the Introduction Section of your notebook. Label the
following apparatus and materials:
FUNNEL, RING STAND, BEAKER, FILTRATE, TRAPPED SAND, STIRRING ROD
DATA:
1. Enter all weights in Table I: Composition of Gravel/Sand/Salt/Sand Mixture.
2. In Table I calculate the mass of each material by subtracting the weight of the empty
beaker from the weight of the beaker filled with that material.
3. Add the masses of each material to obtain the total mass of the mixture after the separation.
Also calculate the mass of the mixture before separation. Enter these results in Table I
also.
4. Calculate the percentage mass of each of the components of the mixture by dividing the mass
of each component by the total mass of the mixture after separation. Enter in Table I.
Provide one sample calculation in the space provided below the data table.
DISCUSSION:
Answer the following questions in complete sentences unless otherwise
specified. In the case of calculations all work must be shown.
1. What property of gravel allowed it to be separate from the mixture ?
2. What property of iron allowed it to be separated from the sand/salt/iron mixture once
the gravel had been removed ?
3. If sand and salt were both magnetic would it have been possible to separate the
sand/salt/iron mixture in the manner you used. What would have happened ?
4. What property of salt allowed it to be separated from the sand ?
5. If sand were soluble in water what would have happened when you tried to filter the
sand/salt/water mixture ?
6. Why can a solution not be successfully filtered ?
7. Explain the difference between dissolving a substance in water and melting a substance.
8. The process of evaporating the water from a filtrate is usually called crystallization.
What property of water allows it to evaporate while the solids that crystallize in the
bottom of the beaker do not evaporate ?
9. If salt, like water, also boiled at 100 ¡C, what would have happened when the salt/water
solution was evaporated under the heat lamp ?
EXPERIMENT #4: SEPARATION OF MIXTURES Page 3 Notebook Page E
Use the names of the following mixtures in your answers to questions 10-13:
GRAVEL/SAND/SALT/IRON mixture SAND/SALT mixture
SAND/SALT/IRON mixture SALT/WATER mixture
SAND/SALT/WATER mixture (immediately after thorough shaking)
10. A "mechanical mixture" is a material which is heterogeneous meaning that it is not the same
throughout; and in which the properties of each component part of the mixture are still recognizable and
not changed in any way. Which of the above mixtures were mechanical mixtures ?
(There are three correct answers)
11. A "suspension" is a material which is homogeneous meaning that it is the same throughout but
cloudy because the particles of the solid are too large to dissolve. The solid in a suspension will usually
eventually settle. Which one of the above mixtures, if any, were suspensions ?
(There is 1 correct answer)
12. A "solution" is a material that is homogeneous and usually transparent or translucent. Some of
the properties of its components disappear. A solution cannot be filtered. Which one of the above
mixtures, if any, were solutions ? (There is one correct answer)
13. For the solution that you named in Question # 12, what are the names of the solute and the solvent ?
CONCLUSION:
1. Make a judgment statement concerning your original hypothesis and comment on your success in
separating the gravel/sand/salt/iron mixture.
2. Calculate the percentage error of your separation of the gravel/sand/salt/iron mixture using the
following formula:
The difference between the weights of the mixture before and after separation divided by the weight of the
mixture before separation (gain or loss) all multiplied by 100. All work must be shown.
3. a. What is a mechanical mixture ? How can it be recognized ?
b. What is a suspension ? How can it be recognized ?
c. What is a solution ? How can it be recognized ?
SOURCES OF ERROR:
INSTRUMENTAL:
PROCEDURAL:
EXPERIMENT #4: SEPARATION OF MIXTURES Notebook Page E
DIAGRAM I: FLOW CHART SCHEME FOR THE SEPARATION OF IRON, SAND, SALT, AND IRON
ORIGINAL MIXTURE
IN BEAKER
GRAVEL , SALT, IRON , SAND
STEP 1 PROCEDURE:
Use a
to separate
APPROVED , , MIXTURE
IN IN
STEP 2 PROCEDURE:
Use a to
separate
APPROVED , MIXTURE
IN BEAKER IN
STEP 3 PROCEDURE:
Add and then
use
to separate
APPROVED , MIXTURE
ON IN
STEP 4 PROCEDURE:
Use
under a HEAT LAMP to
separate
APPROVED
EVAPORATES IN
EXPERIMENT #4: SEPARATION OF MIXTURES Notebook Page E
TABLE I: COMPOSITION OF GRAVEL/SAND/SALT/IRON MIXTURE
MATERIAL NAME OF CONTAINER MASS OF EMPTY MASS OF CONTAINER MASS OF PERCENT
USED FOR WEIGHING CONTAINER FILLED WITH MATERIAL MATERIAL
GRAMS GRAMS GRAMS %
GRAVEL
IRON
SAND
SALT
MIXTURE BEFORE
AFTER
GAIN/LOSS
SAMPLE CALCULATION: (use "AFTER SEPARATION" total mass)
Show your work for calculating the percentage by mass of any one of the materials in your mixture:
Material chosen for sample calculation:
Work: