Download LESSON 16: Crystal Art

LESSON 16: Crystal Art
ESTIMATED TIME Setup: 5 minutes | Procedure: 15–30 minutes
• DESCRIPTION
• MATERIALS
Mix different solid crystals in water, and then use
the solutions to make fun designs on paper.
• OBJECTIVE
This lesson illustrates states of matter, classifications
of matter, and changes between states of matter.
Students mix different substances in water, use the
solutions to paint on paper, and watch as fun crystal
designs appear when the liquid vaporizes. The lesson
can be extended to address the concepts of solubility
and saturation.
• CONTENT TOPICS
Scientific inquiry; states of matter; mixtures
(solutions); physical changes (vaporization)
o Table
salt
Epsom salt
o Sugar
o Cotton swabs
o Clear plastic cups
o Pen
o Masking tape
o Black construction paper
o Teaspoon
o Magnifying glass (optional)
o
Always remember to use the appropriate safety
equipment when conducting your experiment.
Refer to the Safety First section in the Resource Guide
on pages 391–393 for more detailed information about
safety in the classroom.
Jump ahead to page 209 to view the
Experimental Procedure.
NATIONAL SCIENCE EDUCATION STANDARDS SUBJECT MATTER
This lesson applies both Dimension 1: Scientific and Engineering Practices and Dimension 2: Crosscutting Concepts
from “A Framework for K–12 Science Education,” established as a guide for the updated National Science Education
Standards. In addition, this lesson covers the following Disciplinary Core Ideas from that framework:
• PS1.A: Structure and Properties of Matter
• ETS2.A: Interdependence of Science, Engineering, and Technology (see Analysis & Conclusion)
OBSERVATION & RESEARCH
BACKGROUND
Matter exists primarily as a solid, liquid, or gas on the
earth. Gases have no definite shape and no definite
volume. Examples of gases are the oxygen we breathe
and the helium that fills balloons. Liquids have a definite
volume but no definite shape. Examples of liquids are
water and oil. Solids have a definite volume and a
definite shape. Examples of solids are chairs, trees, and
salt. Certain solids, called crystalline solids, are made up
of atoms or molecules that have a specific, repeating
structure. Ice and salt are crystalline solids. Other solids
are made up of atoms or molecules that are locked into
place but do not have a specific, repeating structure.
Those solids are known as amorphous solids. Wax is an
example of an amorphous solid.
Matter can change from one state to another, generally
as a result of a change in temperature. These changes are
physical changes. A physical change is any change in a
substance’s form that does not change its chemical
makeup. The chemical formula of the substance stays the
same before and after the change. For example, tearing
or cutting a piece of paper is an example of a physical
change. The paper is in smaller pieces, but the chemical
makeup of the paper has not changed. Likewise, ice,
water, and water vapor are all H2O in different physical
You Be TheLESSON
Chemist®Activity
Activity
Guide
Guides
| page 206
1:
Goofy
Putty
206
LESSON 16: Crystal Art
states. The chemical formula remains H2O regardless
of whether it is in the solid, liquid, or gaseous state.
FORMULAS & EQUATIONS
Common table salt is mainly made up of the compound
sodium chloride.
Melting is a change in state from a solid to a liquid.
The opposite change is freezing. Freezing is a change
in state from a liquid to a solid. A change in state from
a liquid to a gas is known as vaporization, while a change
in state from a gas to a liquid is known as condensation.
Changes that occur directly between the solid and
gaseous states, without going through the liquid state
first, are less common. Sublimation is a change in state
from a solid directly to a gas. The opposite is deposition,
when a gas changes directly into a solid.
In the experiment, students mix different crystalline
solids in water. A mixture is made of two or more
substances that are combined physically. A solution is a
specific type of mixture. A solution is a uniform mixture
in which one or more substances (solutes) are dissolved
in another substance (solvent). Dissolving sugar or salt in
water creates a solution. The solute is either sugar or salt,
and the solvent is water. The students can then “paint” on
a piece of paper with the different solutions. Over time,
the water will vaporize (becoming water vapor), leaving
behind the solid crystals in fun designs.
The chemical formula for sodium chloride is NaCl.
Most table salts are made of about 97–99% NaCl. The
remaining 1–3% is usually iodine and other ingredients.
Epsomite, commonly known as Epsom salt, is hydrated
magnesium sulfate.
The chemical formula for Epsom salt is
MgSO4 • 7(H2O).
The chemical name for table sugar is sucrose. It is a white,
odorless, crystalline powder with a sweet taste. A molecule
of sucrose is made up of two simple sugars, glucose and
fructose.
Sucrose has the formula C12H22O11.
Tap water is a mixture of pure water, minerals, and other
substances.
The chemical formula for pure water is H2O.
CONNECT TO THE YOU BE THE
CHEMIST CHALLENGE
For additional background information, please
review CEF’s Challenge study materials online at
http://www.chemed.org/ybtc/challenge/study.aspx.
Fun Fact
Diamonds are crystalline
solids. A diamond is the hardest
natural substance and can
scratch glass and most other
gemstones and metals.
• Additional information on physical changes and
states of matter can be found in the Classification
of Matter section of CEF’s Passport to Science
Exploration: The Core of Chemistry.
• Additional information on mixtures and solutions
can be found in the Classification of Matter
section of CEF’s Passport to Science Exploration:
The Core of Chemistry.
HYPOTHESIS
uWhen a salt or sugar solution is used
to “paint” on black paper, fun crystal designs
will remain on the paper after the water vaporizes.
You Be The Chemist® Activity Guide | page 207
LESSON 16: Crystal Art
DIFFERENTIATION IN THE CLASSROOM
LOWER GRADE LEVELS/BEGINNERS
Perform the experiment as described on page 209, but
spend more time on states of matter. Show pictures of
different things and have the students identify the state
of matter.
An important concept directly related to solubility is
saturation. Saturation is the point at which no more of a
solute can be dissolved into a solvent. If you continue to
add a solute to a solution, eventually the additional solute
will no longer dissolve. This point is the saturation point.
Likewise, show images of matter changing states—snow
melting, a pond freezing, etc. Again, have the students
identify which changes they see and how they know.
You may have to show a series of images to illustrate
the changes.
In this experiment, different crystalline solids will be
added to water one teaspoon at a time. When no more
of each solute can be dissolved in the water, the solution
has become saturated. At this point, the solutions will be
used to “paint” on black paper. Over time, the water will
vaporize (becoming water vapor), leaving the solid
crystals behind in fun designs.
HIGHER GRADE LEVELS/ADVANCED STUDENTS
DESCRIPTION
Create various solutions, and use those solutions to make
fun designs on paper.
OBJECTIVE
This lesson explores states of matter, solubility, and
saturation. Students mix different substances in water, use
the solutions to paint on paper, and watch as fun crystal
designs appear as the liquid vaporizes.
OBSERVATION & RESEARCH
Mixtures and solutions are all around us—the air, the
ocean, and the soil are all mixtures in different physical
states. A mixture is made of two or more substances that
are combined physically. A solution is a specific type of
mixture. A solution is a uniform mixture in which one or
more substances (solutes) are dissolved in another
substance (solvent). Dissolving sugar or salt in water
creates a solution. The solute is either sugar or salt, and
the solvent is water.
CONNECT TO THE YOU BE THE
CHEMIST CHALLENGE
For additional background information, please
review CEF’s Challenge study materials online at
http://www.chemed.org/ybtc/challenge/study.aspx.
• Additional information on mixtures and solubility
can be found in the Classification of Matter
section of CEF’s Passport to Science Exploration:
The Core of Chemistry.
• Additional information on solutions and saturation
can be found in the Chemicals by Volume—
Solutions section of CEF’s Passport to Science
Exploration: Chemistry Connections.
In addition, solubility is a physical property that describes
the ability of a chemical substance (the solute) to dissolve
in a solvent to create a uniform solution. A substance that
dissolves in another substance is soluble. For example,
salt is soluble in water. If a substance does not dissolve,
it is insoluble. For instance, butter is insoluble in water.
Several factors can affect solubility, including
temperature, pressure, and the amount of solute or
solvent in a solution.
You Be The Chemist® Activity Guide | page 208
LESSON 16: Crystal Art
EXPERIMENTATION
As the students perform the experiment, challenge them to identify the independent, dependent, and controlled variables,
as well as whether there is a control setup for the experiment. (Hint: If you use a different solute, do the results change?)
Review the information in the Scientific Inquiry section on pages 14–16 to discuss variables.
EXPERIMENTAL PROCEDURE
1. Divide a piece of black construction paper into
three sections. Use masking tape and a pen to label
one section “salt,” a second section “sugar,” and
the third section “Epsom salt.”
2. Take three clear plastic cups, and label them “salt,”
Be sure the water in each cup is the same
temperature to determine which substance
will dissolve the most in water. Increasing
temperature will increase the solubility of all the
substances. At the same temperature, sugar is the
most soluble, followed by table salt, and then
Epsom salt.
“sugar,” and “Epsom salt.”
3. Fill a quarter of each cup with hot tap water, and
place each cup in its section on the black
construction paper.
4. Put one level teaspoon of table salt into the cup
labeled “salt,” and stir with a spoon or swirl the
cup until the salt crystals dissolve (until you can’t
see any or can only see very few crystals against
the black background). Add another teaspoon and
stir or swirl until these crystals dissolve as well.
5. Repeat step 4, continuing to add teaspoons of salt,
DATA COLLECTION
Have students record data in their science notebooks or on
the following activity sheet. How many teaspoons of table
salt can you dissolve in the water? How many teaspoons of
sugar can you dissolve? How many teaspoons of Epsom
salt can you dissolve? You can use the table in the activity
sheet (or a similar one of your own) for students to record
their data.
NOTES
until the water cannot dissolve any more crystals
(when you still see crystals after stirring or swirling).
Record the number of teaspoons used.
6. Repeat steps 4–5 using the sugar and then the Epsom
salt. Record the number of teaspoons of each type of
crystal that dissolved in the water.
7. After each solution is made, dip a cotton swab in the
table salt cup. Use the solution to write your name or
draw a design in the “salt” section on the black
construction paper. Do the same with the other two
liquids using separate cotton swabs.
8. Allow the water to vaporize (15–30 minutes), and
watch as the crystal designs appear.
You Be The Chemist® Activity Guide | page 209
LESSON 16: Crystal Art
ANALYSIS & CONCLUSION
Use the questions from the activity sheet or your own
questions to discuss the experimental data. Ask students
to determine whether they should accept or reject their
hypotheses. Review the information in the Scientific
Inquiry section on pages 14–16 to discuss valid and
invalid hypotheses.
ASSESSMENT/GOALS
Upon completion of this lesson, students should be able
to …
• Apply a scientific inquiry process and perform an
experiment.
REAL-WORLD APPLICATIONS
• Scientists use the process of crystallization to purify
solid compounds. To do this, the solid compound is
dissolved completely in a hot solvent. The hot solution
contains both the desired compound and the
impurities. As the solution cools, the solvent can no
longer hold all of the solute particles, so those particles
begin to crystallize out of the solution. During this
process, each solute particle will approach a growing
crystal and will attach to the crystal surface if it fits the
structure of the crystal (if it is the same type of
molecule). Therefore, the desired solid compound
(solute) is separated from the impurities.
• Compare and contrast solids, liquids, and gases,
and give examples of each.
COMMUNICATION
• Differentiate between crystalline and amorphous
solids.
Discuss the results as a class and review the activity sheet.
Review the information in the Scientific Inquiry section on
pages 14–16 to discuss the importance of communication
to scientific progress.
• Define and identify physical changes between states
of matter.
• Define and identify solutions, solutes, and solvents.
• Explain solubility and saturation (see Differentiation
in the Classroom).
MODIFICATIONS/EXTENSIONS
Modifications and extensions provide alternative methods
for performing the lesson or similar lessons. They also
introduce ways to expand on the content topics presented
and think beyond those topics. Use the following
examples or have a discussion to generate other ideas
as a class.
• To demonstrate the relationship between temperature
and solubility, try the experiment again, but this time,
use refrigerated or cold water. You will find that less
of each substance will dissolve in the water. The
amount of solid solute that can dissolve in a solvent
decreases as the temperature decreases.
You Be The Chemist® Activity Guide | page 210
LESSON 16 ACTIVITY SHEET: Crystal Art
OBSERVE & RESEARCH
1. Write down the materials you see. ____________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
2. How might these materials be used? __________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Example (write or add image)
Gas
Liquid
Solid
Physical change
Melting
Freezing
Vaporization
Condensation
Mixture
Solution
You Be The Chemist®Activity
ActivityGuides
Guide | page 211
LESSON 16 ACTIVITY SHEET: Crystal Art
4. Consider what happens when salt or sugar solutions are applied to black construction paper and why.
uWrite your hypothesis. ______________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
PERFORM YOUR EXPERIMENT
1. Divide a piece of black construction paper into three sections. Use masking tape and a pen to label each section.
Label one section “salt.” Label the second section “sugar.” Label the third section “Epsom salt.”
2. Get three clear plastic cups. Label one “salt.” Label the second “sugar.” Label the third “Epsom salt.”
3. Fill a quarter of each cup with hot tap water. Place each cup in its section on the black construction paper.
4. Put one level teaspoon of table salt into the cup labeled “salt.” Stir with a spoon or swirl the cup until the salt
crystals dissolve. Stir until you can’t see any or can only see very few crystals against the black background. Then,
add another teaspoon of table salt. Stir or swirl until these crystals dissolve as well.
5. Repeat step 4. Continue to add teaspoons of salt until the water cannot dissolve any more crystals. At this point, you
will still see crystals after stirring or swirling. Record the number of teaspoons used.
6. Repeat steps 4–5 using the sugar. Then, repeat steps 4–5 again using the Epsom salt. Record the number of
teaspoons of each type of crystal that dissolved in the water.
7. After each solution is made, dip a cotton swab in the table salt cup. Use the solution to write your name or draw a
design in the “salt” section on the black construction paper. Use two other cotton swabs and do the same with the
other two liquids.
8. Allow the water to vaporize (15–30 minutes). Observe.
You Be The Chemist® Activity Guide | page 212
LESSON 16 ACTIVITY SHEET: Crystal Art
ANALYZE & CONCLUDE
1. In the table below, record the number of teaspoons needed to completely saturate each solution.
Substance
Salt
Sugar
Epsom salt
Number
of Teaspoons
2. Which substance dissolves the most in water? (Into which cup did you add the most teaspoons?) ________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. Which substance dissolves the least in water? __________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
4. What happens when you first write or draw on the paper? Can you see the designs?
__________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
5. What happens after the liquid vaporizes? Can you see the designs? ______________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
6. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist®Activity
ActivityGuides
Guide | page 213
LESSON 16 ACTIVITY SHEET: Crystal Art
EXPAND YOUR KNOWLEDGE—ADVANCED
1. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Example (write or add image)
Solute
Solvent
Soluble
Insoluble
Saturation
2. Is it possible to dissolve more crystals in a saturated solution? How could you do it? ____________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. List other crystal substances. __________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 214
LESSON 16 ACTIVITY SHEET: Crystal Art
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
OBSERVE & RESEARCH
Sugar, table salt, Epsom salt, water, plastic cups, black construction paper …
1. Write down the materials you see. ____________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
Sugar and table salt may be used in cooking. Epsom salt may be used to soothe aches and
2. How might these materials be used? __________________________________________________________________
pains. These substances may be added to water to create solutions and compare their physical properties. Water may be used to drink,
______________________________________________________________________________________________________
bathe, or clean. Black construction paper may be used for drawing or in crafting.
______________________________________________________________________________________________________
3. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Gas
A state of matter that has no definite volume or
shape.
Liquid
A state of matter that has a definite volume but no
definite shape; a liquid will take the shape of the
container that holds it, filling the bottom first.
Solid
A state of matter characterized by a definite volume
and a definite shape; a gas will take the shape of
the container that holds it, filling the entire
container.
Physical change
A change that alters the form or appearance of a
substance but does not change its chemical
makeup or create a new substance.
Melting
A physical change in which a substance changes
states from a solid to a liquid.
Freezing
A physical change in which a substance changes
states from a liquid to a solid.
Vaporization
A physical change in which a substance changes
states from a liquid to a gas.
Condensation
A physical change in which a substance changes
states from a gas to a liquid.
Mixture
A physical combination of two or more substances
that can be physically separated.
Solution
A homogeneous (uniform) mixture in which one or
more substances (solutes) are dissolved in another
substance (solvent).
Example (write or add image)
You Be The Chemist® Activity Guide | page 215
LESSON 16 ACTIVITY SHEET: Crystal Art
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
4. Consider what happens when salt or sugar solutions are applied to black construction paper and why.
When a salt or sugar solution is applied to black construction paper, crystal designs
uWrite your hypothesis. ______________________________________________________________
______________________________________________________________________________________
will eventually appear as the water vaporizes.
______________________________________________________________________________________
PERFORM YOUR EXPERIMENT
1. Divide a piece of black construction paper into three sections. Use masking tape and a pen to label each section.
Label one section “salt.” Label the second section “sugar.” Label the third section “Epsom salt.”
2. Get three clear plastic cups. Label one “salt.” Label the second “sugar.” Label the third “Epsom salt.”
3. Fill a quarter of each cup with hot tap water. Place each cup in its section on the black construction paper.
4. Put one level teaspoon of table salt into the cup labeled “salt.” Stir with a spoon or swirl the cup until the salt
crystals dissolve. Stir until you can’t see any or can only see very few crystals against the black background. Then,
add another teaspoon of table salt. Stir or swirl until these crystals dissolve as well.
5. Repeat step 4. Continue to add teaspoons of salt until the water cannot dissolve any more crystals. At this point, you
will still see crystals after stirring or swirling. Record the number of teaspoons used.
6. Repeat steps 4–5 using the sugar. Then, repeat steps 4–5 again using the Epsom salt. Record the number of
teaspoons of each type of crystal that dissolved in the water.
7. After each solution is made, dip a cotton swab in the table salt cup. Use the solution to write your name or draw a
design in the “salt” section on the black construction paper. Use two other cotton swabs and do the same with the
other two liquids.
8. Allow the water to vaporize (15–30 minutes). Observe.
You Be The Chemist® Activity Guide | page 216
LESSON 16 ACTIVITY SHEET: Crystal Art
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
ANALYZE & CONCLUDE
1. In the table below, record the number of teaspoons needed to completely saturate each solution.
Substance
Salt
Sugar
Epsom salt
Number
of Teaspoons
Answers will vary
Answers will vary
Answers will vary
Answers will vary.
2. Which substance dissolves the most in water? (Into which cup did you add the most teaspoons?) ________________
(In general, sugar dissolves the most in water. It is the most soluble in water.)
______________________________________________________________________________________________________
______________________________________________________________________________________________________
Answers will vary. (In general, the Epsom salt dissolves the least in water. It is the
3. Which substance dissolves the least in water? __________________________________________________________
least soluble in water.)
______________________________________________________________________________________________________
______________________________________________________________________________________________________
4. What happens when you first write or draw on the paper? Can you see the designs?
When you first write on the paper,
__________________________
the paper just appears wet where you applied the solution. You cannot clearly see any designs.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
After the water vaporizes, you can see designs from the
5. What happens after the liquid vaporizes? Can you see the designs? ______________________________________________
crystals left behind.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
6. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________
Answer 1: Valid because the data support my hypothesis.
______________________________________________________________________________________________________
Answer 2: Invalid because the data do not support my hypothesis. I would reject my hypothesis and could form a new one, such as …
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 217
LESSON 16 ACTIVITY SHEET: Crystal Art
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
EXPAND YOUR KNOWLEDGE—ADVANCED
Have students complete this section if you used the advanced differentiation information, or challenge them to find the answers to these
questions at home and discuss how these terms relate to the experiment in class the next day.
1. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Solute
A substance that is dissolved in a solution.
Solvent
A substance capable of dissolving another substance.
Soluble
The ability of a substance to dissolve in another substance.
Insoluble
The inability of a substance to be dissolved into another
substance.
Saturation
The point at which no more of a solute can be dissolved into
a solvent or solution.
Example (write or add image)
It is possible to dissolve more crystals
2. Is it possible to dissolve more crystals in a saturated solution? How could you do it? ____________________________
in a saturated solution. If the solute is a solid, you can heat the solution to dissolve more of the solute. In this experiment, if you heated the
______________________________________________________________________________________________________
saltwater solution, you could dissolve more salt into the solution.
______________________________________________________________________________________________________
Diamonds and other gemstones are examples of crystalline solids. Ice is also a crystalline solid.
3. List other crystal substances. __________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 218