lesson 27: separating salt & pepper - welcome to mrs...

329LESSON 1: Goofy Putty 329LESSON 1: Goofy PuttyYou Be The Chemist Activity Guides | page 329You Be The Chemist Activity Guides | page 329You Be The Chemist Activity Guides | page 329You Be The Chemist® Activity Guide | page 329

LESSON 27: Separating Salt & PepperESTIMATED TIME Setup: 5 minutes | Procedure: 15–20 minutes

• DESCRIPTIONTest different methods to separate a mixture of saltand pepper.

• OBJECTIVEThis lesson demonstrates various separationprocesses. Students explore different techniques forseparating a mixture of salt and pepper based onphysical properties. The lesson can be simplified toreinforce their understanding of different propertiesof matter.

• CONTENT TOPICSScientific inquiry; properties of matter; mixtures;separation processes; elements and compounds;atomic structure

• MATERIALSo Salt

o Pepper o Beakers, glass jars, or plates o A miscellaneous assortment of items for separating

the mixture (spoons, paper towels, tweezers, straws,balloons, magnifying glasses, water, etc.)

Always remember to use the appropriate safetyequipment when conducting your experiment.

Refer to the Safety First section in the Resource Guideon pages 421–423 for more detailed information aboutsafety in the classroom.

Jump ahead to page 332 to view theExperimental Procedure.

OBSERVATION & RESEARCH

BACKGROUNDOften the chemical substances used in science are notfound in their pure or usable form. Instead, they are foundmixed or combined with other substances. For example,pure iron is found in the form of iron ore.

Mixtures are made of two or more substances that arecombined physically, and chemists often need to separatea specific chemical substance (a specific part) from amixture. Separating a mixture of substances into two or more distinct products is called a separation process.A separation process uses the different properties of amixture’s parts to get them to separate. Commonseparation processes include filtration, distillation, andprecipitation.

In this experiment, students will use the physicalproperties of salt and pepper to separate the mixture.Physical properties can be observed by using our sensesand taking measurements. Some examples of physicalproperties are color, texture, weight, shape, boiling point,melting point, and density. Chemical properties can beidentified by observing how a chemical reacts with othersubstances. Some examples of chemical propertiesinclude acidity, toxicity, and flammability.

During the experiment, students can observe the differentphysical properties of the substances, and test methods forusing those properties to separate the mixture. For example,in this lesson, students can use differences in weight toseparate a salt and pepper mixture. Shaking the mixture will

NATIONAL SCIENCE EDUCATION STANDARDS SUBJECT MATTERThis lesson applies both Dimension 1: Scientific and Engineering Practices and Dimension 2: Crosscutting Conceptsfrom “A Framework for K–12 Science Education,” established as a guide for the updated National Science EducationStandards. In addition, this lesson covers the following Disciplinary Core Ideas from that framework: • PS1.A: Structure and Properties of Matter • PS2.B: Types of Interactions • ETS2.B: Influence of Engineering, Technology, and Science on Society and the Natural World (see Analysis & Conclusion)

FORMULAS & EQUATIONSPepper is known as piper nigrum and comes from a plant.The piperine molecule gives the pepper its spicy taste.

Piperine is an alkaloid, and its chemical formula is C17H19NO3.

Common table salt is mainly made up of the compound

sodium chloride.

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.

You Be The Chemist® Activity Guide | page 330

LESSON 27: Separating Salt & Peppercause the lighter pepper to move above the salt, which canthen be scooped off the top. Likewise, lightly blowing onthe mixture will cause the lighter pepper to move awayfrom the heavier salt (though students should be remindedto make sure other students are out of the way when testingthis method). The mixture can also be separated by simplypicking out the crystals or flakes one by one.

Another physical property that can be used to separatethe mixture is electric charge. Substances can gain orlose electrons, becoming positively or negatively charged.Static electricity is the buildup of electric charges on thesurface of an object, which occurs when electrons are pulled from the surface of one material and relocatedonto the surface of another material. Some materials tendto give up electrons easily and become positivelycharged. Other materials tend to collect electrons fromother materials.

In addition, like charges repel one another, while oppositecharges attract one another. Therefore, a positivelycharged object will attract a negatively charged object,but two negatively charged objects will repel one another.

In the experiment, students can rub a balloon against theirhair, causing the balloon to collect electrons from theirhair. Because the balloon is collecting extra electrons, itbecomes negatively charged. After charging the balloon,students can hold it above the salt and pepper mixture andslowly bring it closer. The positively charged pepper will“jump” up quickly and stick to the balloon, leaving the saltbehind. The salt remains on the table because it is heavierthan the pepper. However, if you move the balloon tooclose, the salt will also jump up and attach to the balloon.

HYPOTHESIS

uA mixture of salt and pepper can be

separated by making use of different physical

properties, such as weight, color, and electric charge.

CONNECT TO THE YOU BE THECHEMIST 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 properties of matterand physical separations can be found in theClassification of Matter section of CEF’s Passportto Science Exploration: The Core of Chemistry.

DIFFERENTIATION IN THE CLASSROOM

LOWER GRADE LEVELS/BEGINNERSPerform the experiment as described on page 332, butfocus on classifying matter. Discuss physical propertiesin more detail and the different uses of differentsubstances. Ask students what the physical differencesare between salt and pepper—color, texture, weight, etc.

Another option is to emphasize the different types ofmixtures all around you. Point out different substances in the room, or use pictures of different substances, such as soup, pizza, and apple juice. What do they have in common? What makes them all mixtures? Discuss as a class.

http://www.chemed.org/ybtc/challenge/study.aspx


LESSON 27: Separating Salt & Pepper

HIGHER GRADE LEVELS/ADVANCED STUDENTSDESCRIPTIONA salt and pepper mixture is separated using variousseparation processes.

OBJECTIVEThis lesson encourages students to explore differenttechniques for separating the salt and pepper by making useof the differences in the substances’ properties.

OBSERVATION & RESEARCH Matter is often classified as either a pure substance or amixture. Elements are pure substances that cannot bebroken down further by normal chemical means. Allmatter is made up of basic elements. A compound is apure substance made up of two or more elements joinedin a defined ratio. For example, water is a compoundmade up of the elements hydrogen and oxygen in a 2:1ratio. Two hydrogen atoms and one oxygen atom jointogether to give water the chemical formula H2O.

Mixtures are made of two or more substances that arecombined physically, and chemists often need to separatea specific chemical substance (a specific part) from amixture. Separating a mixture of substances into two or more distinct products is called a separation process.A separation process uses the different properties of amixture’s parts to get them to separate. During theexperiment, students test methods for separating themixture. For example, students can use differences inweight to separate the mixture. Another physical propertythat can be used to separate the mixture is electric charge.

Atoms are the fundamental units of an element and of allmatter! Atoms are made up of even smaller parts—protons, neutrons, and electrons. Protons and neutronsare held together tightly in the nucleus, or core, of anatom, while electrons occupy the space outside of thenucleus. Protons have a positive electric charge, neutronshave no electric charge, and electrons are negativelycharged. When the number of protons in an atom equalsthe number of electrons, the positive and negative chargesare balanced, and the atom is electrically neutral.However, atoms can gain or lose electrons, leaving themwith a positive or a negative charge.

Likewise, larger objects can gain or lose electronsbecoming positively or negatively charged.

Static electricity is the buildup of electric charges on thesurface of an object, which occurs when electrons arepulled from the surface of one material and relocated ontothe surface of another material. Some materials tend to giveup electrons easily and become positively charged. Othermaterials tend to collect electrons from other materials. In addition, like charges repel one another, while oppositecharges attract one another. Therefore, a positivelycharged object will attract a negatively charged object, but two negatively charged objects will repel one another.

In the experiment, students can rub a balloon against theirhair, causing the balloon to collect electrons from the hair.Because the balloon is collecting extra electrons, itbecomes negatively charged. After charging the balloon,students can hold it above the salt and pepper mixture andslowly bring it closer. The positively charged pepper will“jump” up quickly and stick to the negatively chargedballoon, leaving the salt behind. The salt remains on thetable because it is heavier than the pepper. However, if youmove the balloon too close, the salt will also jump up andattach to the balloon.

When the students have completed theexperiment, they should either wipe the balloon

with a damp cloth or wash the balloon off over a sink toremove the pepper. They should be careful not to popthe balloon, or pepper will fly everywhere!

DIFFERENTIATION IN THE CLASSROOM

CONNECT TO THE YOU BE THECHEMIST CHALLENGE

For additional background information, pleasereview CEF’s Challenge study materials online athttp://www.chemed.org/ybtc/challenge/study.aspx.

• Additional information on properties of matter andphysical separations can be found in theClassification of Matter section of CEF’s Passportto Science Exploration: The Core of Chemistry.

• Additional information on atoms and the parts ofan atom can be found in the Atomic Structuresection of CEF’s Passport to Science Exploration:The Core of Chemistry.

http://www.chemed.org/ybtc/challenge/study.aspx

NOTES


LESSON 27: Separating Salt & PepperEXPERIMENTATION

EXPERIMENTAL PROCEDURE

1. Instruct the students to look at the mixture in

a jar or on a plate. Have them write down the

physical properties of the mixture and of the

individual components.

2. As a class, identify physical properties that may

help you separate the mixture.

3. Instruct the students to choose two or three methods

that they could use to separate the mixture using

whatever tools are necessary. (Possible methods

include lightly shaking the mixture, blowing on it,

using a balloon charged with static elecricity, or

picking out the different particles piece by piece.)

Have the students test these methods.

4. While testing their methods, students should record

their results with specific details on how effective

their method was. If they have time, they can do

more testing.

Pepper will sting the eyes. Students should

wear protective eyewear during this

experiment and be warned not to touch their faces.

If students test the technique of blowing to separate

the mixture, they must do it away from other students.

DATA COLLECTION

Have students record data in their science notebooks or on

the following activity sheet. What technique did you try?

What was the result? You can use the table in the activity

sheet (or a similar one of your own) for students to record

their data.

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 different separation processes

are used, will the salt and pepper behave differently?)

Review the information in the Scientific Inquiry section

on pages 14–16 to discuss variables.


LESSON 27: Separating Salt & PepperANALYSIS & 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 anexperiment.

• Identify and understand different properties ofmatter.

• Describe and provide examples of different types ofmixtures.

• Differentiate between physical and chemicalseparation processes.

• Explain electric charges and static electricity.

• Define and provide examples of matter, elements,compounds, and mixtures (see Differentiation in the

Classroom).

• Differentiate between protons, neutrons, and electrons(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.

• Develop a silly story to explain how the salt andpepper got mixed together and why you need to

separate them again. After the experiment, have

students analyze their results and hold a class

discussion about the different methods. Identify

which methods worked the best and why.

• Have the students try using water to separate themixture. The lighter pepper will remain on top of the

water, and the salt will sink to the bottom. The pepper

can be scooped from the top, but what about the salt?

A distillation process can be used to recover the salt.

REAL-WORLD APPLICATIONS

• Separation processes are important in a variety ofindustries. Various separation processes are used in

recycling, food chemistry, refining, water treatment,

and much more. Students can look in books or online

to figure out which separation processes are used in

which industries, as well as how those separation

processes are used.

COMMUNICATION

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.Fun FactDuring the Middle Ages, salt was

extremely valuable for its role in

food preservation. However, during

this time, pepper was even

more expensive than salt.


LESSON 27 ACTIVITY SHEET: Separating Salt & Pepper

OBSERVE & RESEARCH

1. Write down the materials you observe. ________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

2. Predict how these materials may 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)

Mixture

Separation process

Physical property

Chemical property

Static electricity

4. Consider how making use of physical properties can help separate a salt and pepper mixture and why.

uWrite your hypothesis. ______________________________________________________________

______________________________________________________________________________________

______________________________________________________________________________________

You Be The Chemist Activity Guides | page 335You Be The Chemist® Activity Guide | page 335


ANALYZE & CONCLUDE

1. Describe the salt and pepper mixture. __________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

2. Describe the physical properties of the salt. ____________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

3. Describe the physical properties of the pepper. ________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

4. Consider what methods can be used to separate the mixture and test them. Record the results below, noting how

much of the mixture was separated using that method.

PERFORM YOUR EXPERIMENT

1. Observe the mixture of salt and pepper in a jar or on a plate. Record the physical properties of the mixture and the

individual components below.

2. Identify the physical properties of the substances that may help to separate the mixture.

3. Experiment with different separation methods using the different tools supplied by your teacher. Record your results

to determine which method works best to separate the parts of the mixture.

Method Tested Results



5. Which method worked the best? Explain. ________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

6. Based on your experiment, can you think of any other methods that may work well to separate the mixture?

______________________________________________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

7. How is this experiment similar to recycling?______________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

8. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

You Be The Chemist Activity Guides | page 337You Be The Chemist® Activity Guide | page 337


2. Why would scientists need to separate mixtures? (Provide at least one example.) ______________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

EXPAND YOUR KNOWLEDGE—ADVANCED




Element

Compound

Atom

Proton

Neutron

Electron

Electrically neutral


LESSON 27 ACTIVITY SHEET: Separating Salt & PepperANSWER KEY: Below are suggested answers. Other answers may also be acceptable.

OBSERVE & RESEARCH

1. Write down the materials you observe. ________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

2. Predict how these materials may be used. ______________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________




Mixture A physical combination of two or more substancesthat can be physically separated.

Separation process A process that divides a mixture into two or moredistinct substances.

Physical property

A property of a substance that can be experiencedusing the human senses and often detectedthrough a measuring device; physical propertiescan be observed without reacting the substancewith some other substance.

Chemical propertyA property of an object characterized by reactionsthat change the object’s identity; describes anobject’s “potential” to undergo some chemicalchange or reaction due to its composition.

Static electricityThe buildup of electric charges on the surface of anobject, which occurs when electrons are pulledfrom the surface of one material and relocatedonto the surface of another material.

4. Consider how making use of physical properties can help separate a salt and pepper mixture and why.

uWrite your hypothesis. ______________________________________________________________

______________________________________________________________________________________

______________________________________________________________________________________

Salt and pepper may be used to add flavor to food. Plates may be used to hold a

substance. Spoons may be used to scoop or measure a substance. Paper towels may be used to clean up messes. Tweezers may be used

to pick up small objects. These materials may be used to separate a salt and pepper mixture based on the substances’ properties.

Salt, pepper, plates, spoons, paper towels, tweezers, balloons, magnifying glass …

A mixture of salt and pepper can be separated by making use of physical properties,

such as weight, color, and electric charge, because these different properties cause the salt and pepper to behave

differently.



ANALYZE & CONCLUDE

1. Describe the salt and pepper mixture. __________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

2. Describe the physical properties of the salt. ____________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

3. Describe the physical properties of the pepper. ________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

4. Consider what methods can be used to separate the mixture and test them. Record the results below, noting how

much of the mixture was separated using that method.

PERFORM YOUR EXPERIMENT

1. Observe the mixture of salt and pepper in a jar or on a plate. Record the physical properties of the mixture and the

individual components below.

2. Identify the physical properties of the substances that may help to separate the mixture.

3. Experiment with different separation methods using the different tools supplied by your teacher. Record your results

to determine which method works best to separate the parts of the mixture.

Method Tested Results

Shaking the plateAnswers will vary

Picking out the different parts with tweezersAnswers will vary

Using static electricityAnswers will vary

The salt and pepper mixture is black/brown and white …

Salt is a small, rough, crystalline solid ...

Pepper is a small, black/brown, light solid ...



5. Which method worked the best? Explain. ________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

6. Based on your experiment, can you think of any other methods that may work well to separate the mixture?

______________________________________________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

7. How is this experiment similar to recycling?______________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

8. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

Answers will vary depending on the methods used.

Because salt and pepper have different weights, they could be placed in water. The pepper is more likely to remain suspended on the

surface, while the salt will fall to the bottom and may begin to dissolve.

Recycling uses a similar separation process in order to separate different types of

products, such as plastic, glass, or paper, from the rest. Recycling processes will make use of certain characteristics of the products to

separate them from the trash. For example, a magnet is used to separate out some metals.

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 …



2. Why would scientists need to separate mixtures? ______________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

EXPAND YOUR KNOWLEDGE—ADVANCEDHave 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.




ElementA pure substance that cannot be broken down into simplersubstances by ordinary chemical or physical means; anelement is made up of only one type of atom.

Compound A pure substance made up of two or more elements joinedin a defined ratio.

AtomThe fundamental unit of an element; the smallest particleof an element that maintains the chemical properties ofthat element.

Proton A subatomic particle that carries a positive charge and isfound in the nucleus of an atom.

Neutron A subatomic particle that carries no electric charge and isfound in the nucleus of an atom.

Electron A subatomic particle that carries a negative charge andoccupies the space outside the nucleus of an atom.

Electrically neutralAn atomic state in which the number of protons in an atomequals the number of electrons, thus, the positive andnegative charges are balanced.

Scientists need to separate mixtures in order to obtain the parts that make

up these mixtures. Often, the components of a mixture are unknown, and a separation process can show what makes up that mixture.

Separation processes are used to purify water for drinking and to produce different types of fuels from crude oil.

lesson 27: separating salt & pepper - welcome to mrs...

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