Define Chemical Properties Im Going to Do It Again Because It Disappeared From My Phone

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Lesson 6.one

What is a Chemical Reaction?

Key Concepts:

• A physical change, such every bit a state modify or dissolving, does not create a new substance, but a chemical change does.
• In a chemical reaction, the atoms and molecules that collaborate with each other are chosen reactants.
• In a chemic reaction, the atoms and molecules produced by the reaction are called products.
• In a chemical reaction, just the atoms nowadays in the reactants can end upward 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 the products.

Summary

The teacher will use a minor candle flame to demonstrate a chemic reaction between the candle wax and oxygen in the air. Students will see a molecular blitheness of the combustion of methane and oxygen as a model of a similar reaction. Students volition apply atom model cut-outs to model the reaction and see that all the atoms in the reactants prove up in the products.

Objective

Students volition be able to explain that for a chemic 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 as well be able to explain that in a chemic reaction, no atoms are created or destroyed.

Evaluation

Download the student activity sheet, and distribute one per educatee when specified in the activeness. The activity canvass will serve as the "Evaluate" component of each five-E lesson plan.

Condom

Exist sure you and the students article of clothing properly fitting goggles. Be conscientious when lighting the candle. Be sure that the match and candle are completely extinguished when yous are finished with the demonstration.

Materials for the Sit-in

• Tea light candle or other small stable candle
• Matches
• Glass jar, large plenty to exist placed over the candle

Materials for Each Student

• Atom cut-outs from the activity canvas
• Sheet of colored paper or construction paper
• Colored pencils
• Scissors
• Glue or tape

1. Review what happens during a concrete change and introduce the idea of chemical change.

   Tell students that in previous chapters they take studied dissimilar aspects of concrete alter. When atoms and molecules speed upwardly or ho-hum downwardly, that is a physical change. When they change country 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 non really been formed. The ions or molecules tin can still come up back together to class the original substance.

   Allow students know that in this chapter they volition explore what happens during a chemical modify. In a chemic change, the atoms in the reactants rearrange themselves and bond together differently to form i or more new products with different characteristics than the reactants. When a new substance is formed, the alter is called a chemical alter.

2. As a demonstration, light a candle and explicate what is happening using the terms reactants, products, and chemical reaction.

   Explain that in about chemic reactions, two or more substances, called reactants, interact to create different substances called products. Tell students that burning a candle is an example of a chemical reaction.

   Materials for the Demonstration

   • Tea low-cal candle or other pocket-sized stable candle
   • Matches
   • Glass jar, large plenty to be placed over the candle

   Procedure

   1. Advisedly light a tea low-cal candle or other small candle.
   2. Go along the candle burning as you enquire students the questions below. You will put the candle out in the second office of the demonstration.

   Expected Results

   The wick volition catch on burn and the flame will exist sustained by the chemic reaction.

   The post-obit question is non easy and students are not expected to know the answer at this point. However, thinking about a candle called-for in terms of a chemic reaction is a good identify to start developing what it means when substances react chemically.

   Ask students:

   What do you call back are the reactants in this chemical reaction?

   Wax and oxygen from the air are the reactants.

   Students oft say that the string or wick is called-for. Information technology is true that the string of the wick does burn but information technology's the wax on the cord and non so much the string itself that burns and keeps the candle called-for. Explain that the molecules that make up the wax combine with oxygen from the air to brand the products carbon dioxide and water vapor.

   Point out to students that this is one of the major characteristics of a chemical reaction: In a chemical reaction, atoms in the reactants combine in new and unlike ways to form the molecules of the products.

   Students may be surprised that h2o tin can be produced from combustion. Since nosotros utilize h2o to extinguish a burn, it may seem strange that water is actually produced by combustion. You may want to allow students know that when they "burn down" food in their bodies, they too produce carbon dioxide and water.

3. Identify a jar over the candle to help students realize that oxygen is a reactant in the called-for of a candle.

   Remind students that air is a mixture of gases. Explain that when something burns, it reacts with the oxygen in the air.

   Inquire students to make a prediction:

   Will the candle nevertheless burn down if one of the reactants (wax or oxygen) is no longer available?

   Students may approximate that the candle will not burn because both reactants are required for the chemical reaction to continue.

   Procedure

   1. Carefully place a glass jar over the lit candle.

      

   Expected Results

   The flame goes out.

   Enquire students:

   Why do yous think the flame goes out when nosotros put a jar over the candle?

   Placing a jar over the candle limits the amount of oxygen in the air around the candle. Without enough oxygen to react with the wax, the chemical reaction cannot take identify and the candle cannot fire.

   When a candle burns for a while, information technology somewhen gets smaller and smaller. Where does the candle wax go?

   When a candle burns, the candle wax seems to "disappear." Information technology doesn't really disappear, though: Information technology reacts chemically, and the new products go into the air.

   Note: Some curious students may ask what the flame is fabricated of. This is a great question and not picayune to answer. The flame is burning wax vapor. The light of the flame is caused by a procedure called chemiluminescence. Energy released in the chemic reaction makes electrons from dissimilar molecules move to a higher energy state. When the electrons come up dorsum downwards, energy is released in the form of light.

4. Introduce the chemical equation for the combustion of methane and explain that atoms rearrange to go different molecules.

   Explicate to students that wax is made of long molecules called paraffin and that methane series is made up of only carbon atoms and hydrogen atoms bonded together. Molecules made of only carbon and hydrogen are called hydrocarbons. Tell students that you will use the simplest hydrocarbon (methyl hydride) equally a model to evidence how the wax, or whatever other hydrocarbon, burns.

   Project the paradigm Chemical Reaction between Marsh gas and Oxygen.

   Show students that at that place is methane and oxygen on the left side of the chemic equation and carbon dioxide and water on the correct side. Explain that 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 alkane reacted with oxygen in the air to produce carbon dioxide and water, similar to the chemic reaction betwixt methyl hydride and oxygen.

   Explicate to students that the chemic formula for marsh gas is CH_four. This means that methane is made upwardly of one carbon atom and four hydrogen atoms.

   Bear witness students that the other reactant is 2 molecules of oxygen gas. Signal out that each molecule of oxygen gas is made up of two oxygen atoms bonded together. It can be confusing for students that oxygen the atom, and oxygen the molecule, are both called oxygen. Let students know that when we talk near the oxygen in the air, it is always the molecule of oxygen, which is ii oxygen atoms bonded together, or O_ii.

   Ask students:

   Where do the atoms come up from that make the carbon dioxide and the water on the correct side of the equation?

   The atoms in the products come up from the atoms in the reactants. In a chemical reaction, bonds betwixt atoms in the reactants are broken and the atoms rearrange and course new bonds to make the products.

   Note: Leave this equation projected throughout the activeness in the Explore section of this lesson. Students will need to refer to it as they model the chemical reaction.

   Give Each Educatee an Activity Canvass.

   Students volition record their observations and respond questions virtually the activity on the action sheet. The Explicate It with Atoms and Molecules and Accept It Further sections of the activity sheet will either be completed as a class, in groups, or individually, depending on your instructions. Look at the teacher version of the activity sheet to find the questions and answers.

5. Have students make a model to testify that in a chemical reaction the atoms of the reactants rearrange to form the products.

   Question to Investigate

   Where do the atoms in the products of a chemical reaction come from?

   Materials for Each Pupil

   • Cantlet model cut-outs (carbon, oxygen, and hydrogen)
   • Sheet of colored newspaper or construction paper
   • Colored pencils
   • Scissors
   • Glue or record

   Procedure

   1. Prepare the Atoms

      1. Color the carbon atoms black, the oxygen atoms ruby-red, and go out the hydrogen atoms white.
      2. Employ scissors to carefully cutting out the atoms.

   2. Build the Reactants

      1. On a sheet of newspaper, place the atoms together to make the molecules of the reactants on the left side of the chemic equation for the combustion of methyl hydride.

         
      2. Write the chemical formula under each molecule of the reactants. As well draw a + sign between the reactants.

   After you are sure that students take made and written the formula for the reactant molecules, tell students that they volition rearrange the atoms in the reactants to class the products.

   1. Build the Products

      1. Draw an pointer after the second oxygen molecule to testify that a chemical reaction is taking place.
      2. Rearrange the atoms in the reactants to make the molecules in the products on the right side of the arrow.
      3. Write the chemical formula nether each molecule of the products. Also draw a + sign betwixt the products.

   Tell students that in a chemical reaction, the atoms in the reactants come apart, rearrange, and make new bonds to form the products.

   1. Represent the Chemic Equation

      1. Have students employ their remaining atoms to make the reactants again to represent the chemic reaction equally a consummate chemic equation.
      2. Glue or record the atoms to the paper to brand a more than permanent chemical equation of the combustion of methane.

6. Help students count up the number of atoms on each side of the equation.

   Project the animation Moving Chemic Equation for the Combustion of Methyl hydride.

   Show students that the atoms in marsh gas and oxygen need to come apart but like in their models. Also point out that the atoms arrange themselves differently and bond once more to form new products. This is also like their model. Exist certain that students realize that the atoms in the products merely come from the reactants. There are no other atoms available. No new atoms are created and no atoms are destroyed.

   Explain to students that chemical reactions are more than complicated than the simplified model shown in the animation. The animation shows that bonds between atoms in the reactants are broken, and that atoms rearrange and class new bonds to make the products. In reality, the reactants need to collide and interact with each other in society for their bonds to break and rearrange. Likewise, the animation shows all of the atoms in the reactants coming apart and rearranging to grade the products. But in many chemical reactions, only some bonds are broken, and groups of atoms stay together as the reactants class the products.

   Read more about the combustion of methane in the teacher groundwork section.

   Guide students as you answer the post-obit question together:

   How many carbon, hydrogen, and oxygen atoms are in the reactants compared to the number of carbon, hydrogen, and oxygen atoms in the products?

   Show students how to utilize the big number (coefficient) in front of the molecule and the little number afterwards an atom of the molecule (subscript) to count the atoms on both sides of the equation. Explain to students that the subscript tells how many of a certain blazon of atom are in a molecule. The coefficient tells how many of a particular type of molecule at that place are. So if there is a coefficient in front of the molecule and a subscript later an atom, yous need to multiply the coefficient times the subscript to get the number of atoms.

   For example, in the products of the chemical reaction there are 2H₂O. The coefficient ways that in that location are two molecules of h2o. The subscript means that each water molecule has two hydrogen atoms. Since each water molecule has ii hydrogen atoms and in that location are two h2o molecules, at that place must exist 4 (2 × two) hydrogen atoms.

   Table i. Counting atoms on the reactant and production side of the chemic equation for the combustion of methane.

   Atoms	Reactant Side	Production Side
   Carbon
   Hydrogen
   Oxygen

   Note: The coefficients actually point the ratios of the numbers of molecules in a chemical reaction. It is not the actual number equally in two molecules of oxygen and i molecule of methane since there are unremarkably billions of trillions of molecules reacting. The coefficient shows that at that place are twice equally many oxygen molecules as methyl hydride molecules reacting. It would be correct to say that in this reaction there are two oxygen molecules for every methane molecule.

7. Explain that mass is conserved in a chemical reaction.

   Ask students:

   Are atoms created or destroyed in a chemic reaction?

   No.

   How do you know?

   There are the same number of each type of atom on both the reactant side and the product side of the chemical equation we explored.

   In a physical alter, like changing state from a solid to a liquid, the substance itself doesn't really alter. How is a chemical change unlike from a physical alter?

   In a chemic change, the molecules in the reactants interact to form new substances. In a physical change, like a state change or dissolving, no new substance is formed.

   Explain that another style to say that no atoms are created or destroyed in a chemical reaction is to say, "Mass is conserved."

   Project the prototype Balanced Equation.

   Explicate that the balance shows the mass of methane and oxygen on i side exactly equals the mass of carbon dioxide and h2o on the other. When an equation of a chemical reaction is written, it is "balanced" and shows that the atoms in the reactants end upwardly in the products and that no new atoms are created and no atoms are destroyed.

8. Introduce two other combustion reactions and have students bank check to see whether or not they are balanced.

   Tell students that, in addition to the wax and methane, some other common hydrocarbons are propane (the fuel in outdoor gas grills), and butane (the fuel in disposable lighters). Have students count the number of carbon, hydrogen, and oxygen atoms in the reactants and products of each equation to see if the equation is balanced. They should tape the number of each type of atom in the chart on their activity sail.

   

   Lighting an outdoor gas grill—Combustion of propane

   C_iiiH₈ + 5O_two → 3CO_two + 4H_two0

   Using a dispensable lighter—Combustion of butane

   2C₄H₁₀ + 13O_ii → 8CO₂ + 10H_twoO

   After students accept counted up each blazon of atom, review their answers to make sure they know how to interpret subscripts and coefficients.

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Source: https://www.middleschoolchemistry.com/lessonplans/chapter6/lesson1

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