Middle+School+Chemistry+Chapter+6

=Chapter 6, Lesson 1: What is a Chemical Reaction?= media type="custom" key="25101464"

Key Concepts

 * A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does
 * In a chemical reaction, the atoms and molecules that interact with each other are called //reactants//
 * In a chemical reaction, the atoms and molecules produced by the reaction are called //products//
 * In a chemical reaction, only the atoms present in the reactants can end up in the products. No new atoms are created, and no atoms are destroyed
 * In a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make new products

Objective
Students will be able to explain that for a chemical reaction to take place, the bonds between atoms in the reactants are broken, the atoms rearrange, and new bonds between the atoms are formed to make the products. Students will also be able to explain that in a chemical reaction, no atoms are created or destroyed.

Materials Needed

 * Tea light candle
 * matches
 * glass jar, large enough to be placed over the candle
 * atom cut-outs form the activity sheet
 * sheet of colored paper or construction paper
 * colored pencils
 * scissors
 * glue or tape

In previous chapters you studied different aspects of physical change. When atoms and molecules speed up or slow down, that is a physical change. When they change state from liquid to solid or from gas to liquid, that is a physical change. When a substance is dissolved by water or some other solvent, a new substance has not really been formed. The ions or molecules can still com back together to form the original substance.

In this chapter, you will explore what happens during a //chemical// change. In a chemical change, the atoms in the reactant rearrange themselves and bond together differently to form one or more new products with different characteristics than the reactants. When a new substance is formed, the change is called a chemical change.


 * 1) Watch the demonstration and write your observations down on your activity sheet.
 * 2) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_1/combustion_of_methane.jpg width="402" height="111"]]Wax is made of long molecules called //paraffin//, and paraffin is made up of only carbon atoms and hydrogen atoms bonded together. This is a model that shows how methane and oxygen react. The molecules on the left side are the //reactants// and the ones on the right side are the //products.// When the candle was burning, the paraffin reacted with oxygen in the air to produce carbon dioxide and water, similar to the chemical reaction between methane and oxygen.
 * 3) Make a model to show that in a chemical reaction the atoms of the reactants rearrange to form the products. Follow the procedure on your activity sheet.
 * 4) media type="file" key="combustion_of_methane.swf" width="360" height="270"The atoms in methane and oxygen need to come apart just like in your model. Chemical reactions are more complicated than this animation shows.
 * 5) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_1/balanced_equation.jpg width="485" height="134"]]Are atoms created or destroyed in a chemical reaction? This balance shows the mass of methane and oxygen on one side exactly equals the mass of carbon dioxide and water on the other. When an equation of a chemical reaction is written, it is "balanced" and shows that the atoms in the reactants end up in the products and that no new atoms are created and no atoms are destroyed.
 * 6) [[image:http://www.middleschoolchemistry.com/img/content/lessons/6.1/methane_propane_butane.jpg width="389" height="120"]]Complete the Take It Further section of your activity sheet
 * 7) Write the definition of reactant and product in your science notebook.

=Chapter 6, Lesson 2: Controlling the Amount of Products in a Chemical Reaction= media type="custom" key="25200994"

Key Concepts

 * Changing the amount of reactants affects the amount of products produced in a chemical reaction
 * In a chemical reaction, only the atoms present in the reactants can end up in the products
 * Mass is conserved in a chemical reaction

Objective
Students will be able to explain that for a chemical reaction to take place, the bonds between atoms in the reactants are broken, the atoms rearrange, and new bonds between the atoms are formed to make the products. Students will be able to count the number of atoms on the reactant side and on the product side of a chemical equation. They will also be able to explain that the equal number of atoms on each side of the equation shows that mass is conserved during a chemical reaction. Students will also be able to explain, on the molecular level, why changing the amount of one or more reactants changes the amount or products. They will also be able to explain why simply adding more and more of one reactant will eventually not produce additional products.

Materials Needed

 * vinegar
 * baking soda
 * water
 * alka-seltzer
 * detergent solution
 * graduated cylinders
 * measuring spoons
 * plastic cups
 * dropper
 * plastic waste container




 * 1) In the last lesson, you learned that in a chemical reaction certain atoms in the reactant molecules unbond from one another and then rearrange and rebond in different ways to form the products. There were the same type and number of atoms in the reactant as were in the products. Although the reaction in this lesson looks more complicated, these same principles still apply.
 * 2) Watch the demonstration and answer question 1 on your activity sheet
 * 3) Look at the chemical equation above - the first shows the reactants and the second shows the products. Answer question #2 on your activity sheet.
 * 4) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_2/mass_is_conserved.jpg width="492" height="136"]]Count the atoms in the reactants and in the products of the vinegar-baking soda reaction.
 * 5) Complete the activity on your sheet and record your observations.
 * 6) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_2/vinegar_and_baking_soda_3.jpg width="510" height="141"]]This is the chemical equation for the reaction between vinegar and baking soda. Complete the Explain it with Atoms & Molecules section of your activity sheet
 * 7) Complete the Take It Further Section

=Chapter 6, Lesson 3: Forming a Precipitate= media type="custom" key="25202236"

Key Concepts

 * The ions or molecules in two solutions ca react to form a solid
 * A solid formed from two solutions is called a //precipitate//

Objective
Students will be able to explain that for a chemical reaction to take place, the reactants interact, bonds between certain atoms in the reactants are broken, the atoms rearrange, and new bonds between the atoms are formed to make the products.Students will also be able to explain that this definition applies to the production of a solid called a // precipitate. //

Materials Needed

 * Sodium carbonate
 * Epsom salts
 * 2 clear plastic cups
 * test tube
 * water
 * copper II sulfate
 * household ammonia
 * Hydrogen peroxide (3%)
 * graduated cylinder
 * 2 droppers
 * baking soda
 * calcium chloride
 * water
 * measuring spoon
 * masking tape
 * pen
 * safety goggles
 * coffee filter


 * 1) Watch the demonstration & record your observations on your activity sheet.
 * 2) Complete the experiment on your activity sheet and record your observations. **Make sure you wear the safety goggle**
 * 3) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_3/calcium_chloride_sodium_bicarbonate.jpg width="518" height="143" caption="Calcium Chloride and Sodium Bicarbonate"]]Complete the Explain it with Atoms & Molecules section of your activity sheet.
 * 4) How could you separate the precipitate from the other products? Complete the activity to find out & record your observations on your sheet.
 * 5) Watch the demonstration and record your observations in the Take It Further section of your activity sheet
 * 6) Use your molecular kit to complete #9

=Chapter 6, Lesson 4: Temperature and the Rate of a Chemical Reaction= media type="custom" key="25203764"

Key Concepts

 * Reactants must be moving fast enough and hit each other hard enough for a chemical reaction to take place
 * Increasing the temperature increases the average speed of the reactant molecules
 * As more molecules move faster, the number of molecules moving fast enough to react increases, which results in faster formation of products

Objective
Students will be able to identify and control variables to design an experiment to see if temperature affects the rate of a chemical reaction. Students will be able to explain, on the molecular level, why the temperature of the reactants affects the speed of the reaction

Materials Needed

 * hot water in an insulated cup
 * ice water in an insulated cup
 * 2 glow sticks
 * baking soda
 * calcium chloride
 * water
 * graduated cylinder
 * measuring spoon
 * 2 wide clear plastic cups
 * 4 small clear plastic cups
 * 2 plastic deli-style containers
 * masking tape
 * pen
 * safety goggles


 * 1) How does warming or cooling a glow stick affect its chemical reaction? Watch the demonstration and write your observations on your activity sheet.
 * 2) Does the temperature of the reactants affect the rate o the chemical reaction? Follow the procedure on your activity sheet to find out and record your observations.
 * 3) media type="file" key="molecules_collide.swf" width="360" height="270"The slower-moving molecules hit and bounce off without reacting. But the faster-moving molecules hit each other with enough energy to break bonds and react.
 * 4) media type="custom" key="25246000"This reaction requires heat to get started but produces enough heat to keep reacting. A common burning candle works the same way. The wax of the candle and oxygen do not react until the heat of a match is added. Then, the heat from the burning wax supplies the heat to keep the reaction going.

=Chapter 6, Lesson 5: A Catalyst and the Rate of Reaction= media type="custom" key="25246060"

Key Concepts

 * A catalyst is a substance that can help the reactants in a chemical reaction react with each other faster.
 * A catalyst doe snot actually become part of the products of the reaction.

Objective
Students will be able to define a catalyst as a substance that increases the rate of a chemical reaction but is not incorporated into the products of the reaction.

Materials Needed

 * graduated cylinder
 * hydrogen peroxide
 * yeast
 * 2 Popsicle sticks
 * salt aluminum foil
 * thermometer
 * detergent solution
 * dropper
 * small cup
 * clear plastic cup
 * copper II sulfate solution (in cup)

Watch the two videos that show demonstrations where water vapor and oxygen gas are produced in the exact same chemical reaction. Because gases are invisible, watch closely for evidence that a gas is produced. media type="file" key="elephant_toothpaste.wmv" width="300" height="300"media type="file" key="genie_in_a_bottle.wmv" width="300" height="300"


 * 1) How could you tell that a gas is produced in the chemical reaction? Write your answer on your activity sheet.
 * 2) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_5/hydrogen_peroxide_decomposition.jpg width="380" height="105"]]Hydrogen peroxide is not very stable and breaks down into water and oxygen on its own. This kind of change is a chemical reaction called //decomposition.// The decomposition of hydrogen peroxide is very slow and is not usually noticeable. Hydrogen peroxide decomposes to form water and oxygen according to the equation shown above.
 * 3) Can another substance catalyze the decomposition of hydrogen peroxide? Follow the procedure on your activity sheet to find out and record your observations.
 * 4) Complete the Take It Further activity to determine the catalyst. Record your observations on your activity sheet.

=Chapter 6, Lesson 6: Using Chemical Change to Identify an Unknown= media type="custom" key="25246418"

Key Concepts

 * Substances react chemically in characteristic ways
 * A set of reactions can be used to identify an unknown substance

Objective
Students will be able to identify and control variables to develop a test to identify an unknown powder. Students will be able to explain that a substance reacts chemically in characteristic ways and that these characteristics can be used to identify an unknown substance.

Materials Needed

 * baking soda
 * cornstarch
 * cream of tartar
 * tincture of iodine
 * vinegar
 * water
 * universal indicator
 * graduated cylinder
 * 4 droppers
 * teaspoons
 * clear plastic cups
 * 3 Popsicle sticks
 * testing chart


 * 1) Watch the demonstration and record your observations on your activity sheet.
 * 2) You will test four different similar-looking powders with four different test solutions. Use the testing chart to separate and keep track of your ingredients.
 * 3) Can you use the characteristic ways substances react to tell similar-looking substances apart? Follow the procedure on your activity sheet and record your observations.
 * 4) Can you use the characteristic ways substances react to identify an unknown powder? Follow the procedure on your activity sheet and record your observations.
 * 5) Complete the Take It Further section on your activity sheet.
 * 6) Watch the demonstration and record your observations.

=Chapter 6, Lesson 7: Energy Changes in Chemical Reactions= media type="custom" key="25246834"

Key Concepts

 * If two substances react and the temperature of the mixture decreases, the reaction is endothermic
 * If two substances react an the temperature of the mixture increases, the reaction is exothermic
 * A chemical reaction involves the breaking of bonds in the reactants and the forming o bonds in the products
 * It takes energy t break bonds
 * Energy is released when bonds are formed
 * If a reaction is endothermic, it takes more energy to break the bonds of the reactants than is released when the bonds of the products are formed
 * If a reaction is exothermic, more energy is released when the bonds of the products are formed than it takes to break he bonds of the reactants

Objective
Students will be able to define an endothermic and exothermic reaction. Students will be able to use the concept of energy in bond breaking and bond making to explain why one reaction can be endothermic an another reaction can be exothermic.

Materials Needed

 * vinegar
 * baking soda
 * calcium chloride
 * water
 * thermometer
 * 4 small cups
 * disposable self-heating hand warmer
 * self-inflating balloon
 * magnesium sulfate
 * sodium carbonate
 * citric acid
 * universal indicator


 * Watch the following videos of three chemical reactions where the temperature increases dramatically.**


 * 1) Thermite Reaction media type="custom" key="25246874"
 * 2) media type="custom" key="25246912"Nitrogen Triiodide Reaction
 * 3) White Phosphorous Reaction
 * 4) Measure the change in temperature of the reaction between baking soda and vinegar. Follow the procedure on your activity sheet and record your observations.
 * 5) Does the temperature increase, decrease, or stay the same in the reaction between baking soda solution and calcium chloride? Follow the procedure on your activity sheet and record your observations.
 * 6) media type="file" key="endothermic_reaction.swf" width="360" height="270"Endothermic Reaction - A chemical reaction involves the breaking of bonds in the reactants and the making of binds in the products.
 * 7) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_7/baking_soda_and_vinegar.jpg width="434" height="120"]]Is this an endothermic or exothermic reaction?
 * 8) media type="file" key="exothermic_reaction.swf" width="360" height="270"Exothermic Reaction - An exothermic reaction takes less energy to break the bonds of the reactants than is released when the bonds in the products are formed.
 * 9) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_7/baking_soda_and_calcium_chloride.jpg width="460" height="127"]]Is this an endothermic or exothermic reaction?
 * 10) Complete the Take It Further section of your activity sheet and record your observations. (We will make our own self-inflating balloon)
 * 11) What clues do you observe that a chemical reaction is taking place? Complete the Extra Extend procedure on your activity sheet.

=Chapter 6, Lesson 8: pH and Color Change= media type="custom" key="25638120"

Key Concepts

 * Whether a solution is acidic or basic can be measured on the pH scale
 * When universal indicator is added to a solution, the color change can indicate the approximate pH of the solution
 * Acids cause universal indicator solution to change from green toward red
 * Bases cause universal indicator to change from green toward purple
 * Water molecules (H20) can interact with one another to form H30+ ions and OH- ions
 * At a pH of 7, there are equal numbers of H3O+ ions and OH- ions in water, and this is called a neutral solution
 * Acidic solutions have a pH below 7 on the pH scale
 * Basic solutions have a pH above 7 on the pH scale

Objective
Students will be able to explain, on the molecular level, that pH is a measure of the concentration of the H3O+ ions in water and that adding an acid or a base to water affects the concentration of these ions.

Materials Needed

 * 3 clear plastic cups
 * Masking tape
 * permanent marker
 * sodium carbonate
 * universal indicator solution
 * water
 * pH color chart
 * citric acid
 * graduated cylinder
 * flat toothpicks
 * droppers




 * 1) Watch the demonstration and record your observations on your activity sheet. Do you think what happened was a chemical reaction? Why or why not?
 * 2) Review the Universal Indicator pH Color Chart. The chart shows the range of color changes for universal indicator when acidic or basic solutions are added to the indicator. Compare the color of the solutions made in the demonstration to the colors on the chart.
 * 3) Complete the procedure on your activity sheet and record your observations. Wear safety goggles throughout this process of making solutions.
 * 4) How does the concentration of citric acid affect the color of universal indicator solution? Complete the activity and record your observations.
 * 5) Hos does the concentration of sodium carbonate affect the color of universal indicator solution? Complete the activity and record your observations.
 * 6) media type="file" key="proton_transfer.swf" width="360" height="270"Each hydrogen atom in a water molecule has both a proton and an electron. The hydrogen atoms share their electrons with the oxygen atom.
 * 7) [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_8/proton_transfer.jpg width="283" height="220"]]This illustration shows the chemical equations that explain how water molecules can become ions and how ions can become water molecules again.
 * 8) media type="file" key="acids_donate_protons.swf" width="360" height="270"When an acid is added to an indicator solution, the acid donates protons to the water molecules.
 * 9) media type="file" key="bases_accept_protons.swf" width="360" height="270"When a base is added to an indicator solution, it accepts protons from the water molecules, creating OH++ ions.
 * 10) How do you think the color will change if you pour a small amount of each leftover solution into your universal indicator solution? Complete the Extend portion of your activity sheet and record your observations.

=Chapter 6, Lesson 9: Neutralizing Acids and Bases= media type="custom" key="25706362"media type="custom" key="25706404"

Key Concepts

 * pH is a measure of the concentration of H3O+ ions in a solution
 * Adding an acid increases the concentration of H3O+ ions in the solution
 * Adding a base decreases the concentration of H3O+ ions in the solution
 * An acid and a base are like chemical opposites
 * If a base is added to an acidic solution, the solution becomes less acidic and m oves toward the middle of the pH scale. This is called neutralizing the acid
 * If an acid is added to a basic solution, the solution becomes less basic and moves toward the middle of the pH scale. This is called neutralizing the base

Objective
Students will be able to explain, on the molecular level, that pH is affected by the concentration of the H3O+ ions in water. They will also be able to explain why adding a base to an acid or an acid to a base can mak the pH of the solution closer to 7.

Materials Needed

 * 4 clear plastic cups
 * graduated cylinder
 * universal indicator
 * water
 * sodium carbonate
 * citric acid
 * flat toothpicks
 * 2 droppers
 * masking tape and pen
 * spot plate


 * 1) What color will the green indicator solution turn if citric acid solution is added? What do you think you could add to the reddish indicator to make it less acidic and go back toward green? Watch the demonstration and record you observations on your activity sheet.
 * 2) Acids and bases are like chemical opposites. You will experiment to figure out how many drops of a basic solution it takes to cause an acidic solution to move to the middle of the pH scale. This is called neutralizing the acid. Follow the activity on your sheet and record your observations.
 * 3) media type="file" key="neutralizing_an_acidic_solution.swf" width="360" height="270" By adding drops of citric acid to the indicator solution it increased the concentration of H3O+ ions. When you add a base to this acidic solution, the base accepts protons from the water molecules creating OH- ions.
 * 4) How many drops of sodium carbonate solution will it take to neutralize a more concentrated citric acid solution? Complete the second activity on your sheet and record your observations.
 * 5) Complete the Take It Further section to determine which solution is a more concentrated basic solution. Record your observations.

=Chapter 6, Lesson 10: Carbon Dioxide can Make a Solution Acidic= media type="custom" key="25874882"media type="custom" key="25874894"

Key Concepts

 * Carbon dioxide (CO2) gas dissolved in water can cause water to become acidic
 * The acidity of water from dissolved CO2 can be reduced by a base such as baking soda (sodium bicarbonate)

Objective
Students will be able to explain that carbon dioxide from any source reacts chemically with water to form carbonic acid. They will also be able to use the color changes of universal indicator to monitor the changing pH of a solution during a chemical reaction.

Materials Needed

 * universal indicator solution
 * water
 * universal indicator pH color chart
 * carbonated water (club soda)
 * baking soda in side, clear, plastic cup
 * vinegar
 * alka-seltzer tablet
 * 2 small clear plastic cups
 * straw
 * 4 wide clear plastic cups
 * 4 taller, clear, plastic cups
 * graduated cylinder
 * snack-sized zip-closing plastic bag


 * 1) Does blowing into the indicator solution change its pH? Does the solution become a little more acidic or a little more basic? Watch the demonstration and record your observations on your activity sheet.
 * 2) Will carbon dioxide from carbonated water change the pH of an indicator solution? Complete the activity and record your observations.
 * 3) Will carbon dioxide gas produced in the baking soda and vinegar reaction change the pH of an indicator solution? Complete the second procedure and record your observations on your activity sheet.
 * 4) What did carbon dioxide from breath, carbonated water, and the baking soda and vinegar reaction all do to water? [[image:http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_10/co2_reacting_with_water.jpg]] Carbon dioxide reacts with water to produce carbonic acid. The double arrow in this equation meas that carbonic acid breaks down readily to form carbon dioxide and water again.
 * 5) How does the pH of the solution change during a chemical reaction between the ingredients in an Alka-Seltzer tablet in water? Complete the Take It Further section and record your observations.
 * 6) Too much CO2 in the atmosphere can cause something called the greenhouse effect, which makes Earth and its atmosphere warmer. But CO2 can do something else, too much carbon dioxide can cause water to become too acidic. This can be a big problem for fish, aquatic plants, and especially coral. Research questions, such as the following:
 * What is coral and why would too much acid be bad for them?
 * How could we reduce the amount of CO2 that gets into the atmosphere?
 * Even if a large amount of CO2 gets in the atmosphere, what could we do to trap some of it so that it doesn't get into the oceans?

media type="file" key="165_aragonitesaturation.mp4" width="300" height="300"

Some websites to do further research: Understanding Ocean Acidification What is Ocean Acidification? OA Virtual Lab (Click on Show HTML) - complete the online experiment Ocean Acidification Lots of videos and interactive presentations to view

=Chapter 6, Lesson 11: Review and Reflect=
 * 1) Review activity sheets and notes from Chapter 6
 * 2) Complete Chapter 6 reading: [[file:chapter6_student_reading.pdf]]
 * 3) Chapter 6 assessment