329 LESSON 1: Goofy Putty 329 LESSON 1: Goofy Putty You Be The Chemist Activity Guides | page 329 You Be The Chemist Activity Guides | page 329 You Be The Chemist Activity Guides | page 329 You Be The Chemist ® Activity Guide | page 329 LESSON 27: Separating Salt & Pepper ESTIMATED TIME Setup: 5 minutes | Procedure: 15–20 minutes • DESCRIPTION Test different methods to separate a mixture of salt and pepper. • OBJECTIVE This lesson demonstrates various separation processes. Students explore different techniques for separating a mixture of salt and pepper based on physical properties. The lesson can be simplified to reinforce their understanding of different properties of matter. • CONTENT TOPICS Scientific inquiry; properties of matter; mixtures; separation processes; elements and compounds; atomic structure • MATERIALS o 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 safety equipment when conducting your experiment. Refer to the Safety First section in the Resource Guide on pages 421–423 for more detailed information about safety in the classroom. Jump ahead to page 332 to view the Experimental Procedure. OBSERVATION & RESEARCH BACKGROUND Often the chemical substances used in science are not found in their pure or usable form. Instead, they are found mixed 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 are combined physically, and chemists often need to separate a specific chemical substance (a specific part) from a mixture. Separating a mixture of substances into two or more distinct products is called a separation process. A separation process uses the different properties of a mixture’s parts to get them to separate. Common separation processes include filtration, distillation, and precipitation. In this experiment, students will use the physical properties of salt and pepper to separate the mixture. Physical properties can be observed by using our senses and taking measurements. Some examples of physical properties are color, texture, weight, shape, boiling point, melting point, and density. Chemical properties can be identified by observing how a chemical reacts with other substances. Some examples of chemical properties include acidity, toxicity, and flammability. During the experiment, students can observe the different physical properties of the substances, and test methods for using those properties to separate the mixture. For example, in this lesson, students can use differences in weight to separate a salt and pepper mixture. Shaking the mixture will 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 • PS2.B: Types of Interactions • ETS2.B: Influence of Engineering, Technology, and Science on Society and the Natural World (see Analysis & Conclusion)
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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.
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.
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 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. ______________________________________________________________
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.
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)
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.