what must be true about two objects for conduction to take place?

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Lesson 2.1

Heat, Temperature, and Conduction

Central Concepts

• Adding energy (heating) atoms and molecules increases their motion, resulting in an increment in temperature.
• Removing energy (cooling) atoms and molecules decreases their motion, resulting in a decrease in temperature.
• Energy tin can be added or removed from a substance through a process chosen conduction.
• In conduction, faster-moving molecules contact slower-moving molecules and transfer energy to them.
• During conduction the slower-moving molecules speed up and the faster-moving molecules slow down.
• Temperature is a measure of the average kinetic free energy of the atoms or molecules of a substance.
• Heat is the transfer of energy from a substance at a higher temperature to a substance at a lower temperature.
• Some materials are ameliorate conductors of estrus than others.

Summary

Students will practise an action in which heat is transferred from hot water to metal washers and and then from hot metallic washers to water. Students volition view a molecular animation to meliorate understand the process of conduction at the molecular level. Students will also describe their own model of the process of conduction.

Objective

Students volition exist able to draw and draw a model, on the molecular level, showing how energy is transferred from 1 substance to some other through conduction.

Evaluation

Download the student action sail, and distribute one per pupil when specified in the activity. The activity sheet volition serve equally the "Evaluate" component of each 5-E lesson program.

Safety

Make certain you lot and your students clothing properly fitting goggles.

Materials for Each Group

• 2 sets of large metal washers on a cord
• Styrofoam cup filled with hot h2o
• Room-temperature h2o
• 2 thermometers
• Graduated cylinder or beaker

Materials for the Teacher

• 1 Styrofoam loving cup
• Thermometer
• Hot plate or coffee maker
• Large chalice or coffee pot

Annotation: Energy tin can besides exist transferred through radiation and convection, but this affiliate just deals with heat transfer through conduction.

1. Discuss what happens when a spoon is placed in a hot liquid like soup or hot chocolate.

   Ask students:

   Did you always put a metal spoon in hot soup or hot chocolate and then touch the spoon to your mouth? What do you call up might exist happening, betwixt the molecules in the soup and the atoms in the spoon, to make the spoon go hot?

   Information technology's non necessary for students to answer these questions completely at this time. It is more important that they begin to think that something is going on at the molecular level that causes one substance to be able to make another hotter.

   Give each student an activity canvass.

   Students will tape their observations and answer questions near the activity on the activity canvas. The Explain It with Atoms & Molecules and Take Information technology Further sections of the activity sheet will either exist completed as a course, in groups, or individually depending on your instructions. Look at the teacher version of the activity sheet to detect the questions and answers.

2. Accept students explore what happens when room-temperature metallic is placed in hot water.

   If yous cannot get the materials for all groups to do this activity, yous can do the activeness as a demonstration or show students the videos Heating Washers and Cooling Washers.

   Question to investigate

   Why does the temperature of an object change when it is placed in hot h2o?

   Materials for each group

   • 2 sets of large metal washers on a string
   • Styrofoam cup filled with hot water
   • Room-temperature water
   • ii thermometers
   • Graduated cylinder or beaker

   Materials for the teacher

   • 1 Styrofoam cup
   • Thermometer
   • Hot plate or java maker
   • Large beaker or coffee pot

   Teacher grooming

   • Use a cord to tie 5 or vi metal washers together as shown. Each grouping of students volition need two sets of washers, each tied with a string.
   • Hang one ready of washers for each grouping in hot water on a hot plate or in h2o in a java maker so that the washers can get hot. These washers will need to remain hot until the 2nd one-half of the activeness.
   • The other set up should be left at room-temperature and may exist distributed to students along with the materials for the activity.
   • Immediately earlier the activity, pour about 30 milliliters (two tablespoons) of hot h2o (about 50 °C) into a Styrofoam cup for each group. Be sure to pour one cup of hot water for you to utilize as a control.

   Tell students that they are going to see if the temperature of hot water changes every bit a consequence of placing room-temperature metal washers in the water. The just style to tell if the washers cause the temperature to change is to accept a loving cup of hot h2o without washers. Explain that y'all will have this cup of hot water, which volition be the control.

   You will need to place your thermometer in the cup of hot water at the same fourth dimension the students do. Take students record the initial temperature of the control in their charts on the activity sheet, forth with the initial temperature of their own loving cup of hot water. The temperature of the two samples should be about the same.

   Procedure

   1. Place a thermometer in your cup to measure the initial temperature of the h2o. Tape the temperature of the h2o in the "Before" cavalcade in the chart on the activity sheet. Be certain to besides record the initial temperature of the water in the command loving cup.

   2. Use some other thermometer to measure the temperature of the washers. Record this in the "Earlier" column.

      

   Annotation: It is a fiddling awkward to take the temperature of the washers with a regular thermometer because there is such a pocket-size point of contact between the bulb of the thermometer and the surface of the washers. The washers should exist about room-temperature.

   Enquire students to make a prediction:

   • What volition happen to the temperature of the h2o and the washers if you place the washers into the hot water?

   1. With the thermometer all the same in the water, agree the string and lower the metallic washers all the fashion into the hot water.

      
   2. Observe any modify in the temperature of the water. Leave the washers in the water until the temperature stops changing. Record the temperature of the water in each cup in the "After" cavalcade.

   Table 1. Temperature readings for room temperature washers placed in hot h2o

   Temperature of …	Before	After
   H2o in your cup
   Water in the control cup
   Metal washers

   1. Remove the washers from the h2o. And then accept and record the temperature of the washers in the "After" column.
   2. Empty the cup in a waste container or sink.

   Expected results

   The temperature of the h2o will decrease a bit and the temperature of the washers will increment a bit. The amount of temperature subtract and increase is really not that of import. What is important is that there is a temperature subtract in the water and a temperature increase in the washers.

   Read more about energy and temperature in the teacher background department.

   Notation: Eventually two objects at different temperatures that are in contact will come to the same temperature. In the activity, the washers and water will most likely be dissimilar temperatures. For the purposes of this activity, the washers and water are simply in contact for a short time, and then most likely will non come to the aforementioned temperature.

   Students may ask why the temperature of the water went downwards past a unlike amount than the temperature of the washers went upward. The aforementioned corporeality of free energy left the water every bit went into the washers, but it takes a different corporeality of energy to change the temperature of different substances.

3. Take students explore what happens when hot metallic is placed in room-temperature water.

   Ask students:

   • How do y'all retrieve the temperature will change if you place hot washers into room-temperature water?

   Pour about thirty milliliters of room-temperature water into the control cup. Place a thermometer in the cup and tell students the temperature of the water.

   • Pour about xxx milliliters of room-temperature h2o into your Styrofoam loving cup.
   • Identify a thermometer into the water and record its temperature in the "Before" cavalcade in the chart on the activity sheet. Exist certain to besides tape the initial temperature of the water in the control cup.
   • Remove the washers from the hot water where they have been heating and quickly utilize a thermometer to measure the temperature of the washers. Tape this in the "Earlier" cavalcade on your activeness sheet.
   • With the thermometer however in the water, concord the string and lower the hot metal washers all the mode into the h2o.
   • Observe whatsoever change in the temperature of the h2o. Leave the washers in the water until the temperature stops changing. Record the temperature of the water in your loving cup in the "After" column in the chart below. Besides record the temperature of the water in the control cup.
   • Remove the washers from the h2o. Take and tape the temperature of the washers.

   Tabular array ii. Temperature readings for hot washers placed in room-temperature h2o

   Temperature of …	Before	After
   H2o in your cup
   Water in the control cup
   Metal washers

   Expected results

   The temperature of the water increases and the temperature of the washers decreases.

4. Discuss educatee observations and what may have caused the temperature of the metal washers and water to change.

   Ask students:

   How did the temperature of the washers and water change in both parts of the action?

   Based on their data, students should realize that the temperature of both the washers and water inverse.

   Knowing what yous do about heating and cooling atoms and molecules, why practice yous remember the temperature inverse?

   If necessary, guide students' thinking about why the temperature of each changed past request them which were probably moving faster, the atoms in the metallic washers or the molecules in the water. Tell students that the molecular model animation you lot will bear witness next will show them why the temperature of both changed.

5. Evidence two animations to assistance students understand how energy is transferred from one substance to another.

   Testify the molecular model animation Heated Spoon.

   Point out to students that the h2o molecules in the hot h2o are moving faster than the atoms in the spoon. The h2o molecules strike the atoms of the spoon and transfer some of their energy to these atoms. This is how the free energy from the water is transferred to the spoon. This increases the movement of the atoms in the spoon. Since the move of the atoms in the spoon increases, the temperature of the spoon increases.

   It is not easy to observe, but when the fast-moving water molecules striking the spoon and speed upwards the atoms in the spoon, the water molecules slow down a little. And then when energy is transferred from the water to the spoon, the spoon gets warmer and the water gets cooler.

   Explicate to students that when fast-moving atoms or molecules hitting slower-moving atoms or molecules and increase their speed, energy is transferred. The energy that is transferred is chosen heat. This energy transfer process is called conduction.

   Evidence the molecular model blitheness Cooled Spoon.

   Point out to students that in this case, the atoms in the spoon are moving faster than the water molecules in the common cold water. The faster-moving atoms in the spoon transfer some of their free energy to the water molecules. This causes the water molecules to movement a fiddling faster and the temperature of the water to increase. Since the atoms in the spoon transfer some of their energy to the water molecules, the atoms in the spoon slow downwards a footling. This causes the temperature of the spoon to decrease.

   Enquire students:

   Describe how the procedure of conduction acquired the temperature of the washers and water to change in the action.

   Room-temperature washers in hot h2o

   When the room-temperature washers are placed in hot water, the faster-moving h2o molecules hitting the slower-moving metal atoms and make the atoms in the washers move a little faster. This causes the temperature of the washers to increase. Since some of the energy from the water was transferred to the metal to speed them up, the motility of the water molecules decreases. This causes the temperature of the water to decrease.

   Hot washers in room-temperature water

   When the hot metallic washers are placed in the room temperature water, the faster-moving metal atoms hit the slower-moving water molecules and brand the water molecules motion a niggling faster. This causes the temperature of the h2o to increment. Since some of the energy from the metal atoms was transferred to the water molecules to speed them upward, the motion of the metal atoms decreases. This causes the temperature of the washers to decrease.

6. Discuss the connection between molecular motion, temperature, and conduction.

   Ask students:

   How does the motion of the atoms or molecules of a substance affect the temperature of the substance?

   If the atoms or molecules of a substance are moving faster, the substance has a higher temperature. If its atoms or molecules are moving slower, then information technology has a lower temperature.

   What is conduction?

   Conduction occurs when two substances at different temperatures are in contact. Free energy is always transferred from the substance with the higher temperature to the 1 at lower temperature. Every bit free energy is transferred from the hotter substance to the colder one, the colder substance gets warmer and the hotter substance gets cooler. Somewhen the ii substances go the same temperature.

   Students tend to understand heating merely often have a misconception about how things are cooled. Only like heating a substance, cooling a substance also works by conduction. But instead of focusing on the slower-moving molecules speeding up, you focus on the faster-moving molecules slowing down. The faster-moving atoms or molecules of the hotter substance contact slower-moving atoms or molecules of the cooler substance. The faster-moving atoms and molecules transfer some of their energy to the slower-moving atoms and molecules. The atoms and molecules of the hotter substance slow downward, and its temperature decreases. An object or substance can't become colder by adding "coldness" to information technology. Something can just go colder by having its atoms and molecules transfer their energy to something that is colder.

7. Have students draw molecular models to show conduction betwixt a spoon and water.

   Note: In the model you volition show students, the alter in speed of both the water molecules and the atoms in the spoon is represented with different numbers of motion lines. Students may recollect that when atoms or molecules move faster, they get further apart, and when they motion slower, they get closer together. For this activity, the change in distance betwixt water molecules or between atoms in the spoon is not the focus, and therefore it is non shown in the model. You could tell students that models can emphasize one characteristic over some other, in order to assistance focus on the master betoken being represented.

   Room-temperature spoon placed in hot water

   Project the illustrations Spoon in Hot Water Before & Afterward from the activity sheet.

   Take students look at the movement lines in the "Earlier" picture on their activity sheet. Then ask students how the motion of the atoms and molecules would change in the "After" motion picture. The action canvass, along with the image you are projecting, does not accept move lines drawn in the "Afterwards" picture show. Putting these in correctly is the students' task.

   Tell students to add move lines to the "After" illustration and add together descriptive words like "warmer" or "libation" to describe the change in temperature of the water and the spoon.

   Hot spoon placed in room-temperature h2o

   Project the illustrations Hot spoon in room-temperature water before & afterwards from the action sail

   Have students await at the second set of "Before" and "After" pictures. Tell students to add motility lines to the "After" illustration and add descriptive words like "warmer" or "cooler" to describe the change in temperature of the water and the spoon.

8. Show a simulation to illustrate that temperature is the average kinetic energy of atoms or molecules.

   The following simulation shows that at whatsoever temperature, the atoms or molecules of a substance are moving at a variety of speeds. Some molecules are moving faster than others, some slower, only most are in-between.

   Note: Afterwards pressing "Start", the simulation works best if you cycle through all the buttons before using information technology for instruction with students..

   Evidence the simulation Temperature.

   • After cycling through the "Cold", "Medium", and "Hot" buttons, choose "Medium" to begin the discussion with students. Tell students that this simulation shows the relationship between energy, molecular motion, and temperature.

   Tell students that anything that has mass and is moving, no affair how big or small, has a certain amount of free energy, chosen kinetic energy. The temperature of a substance gives yous data well-nigh the kinetic energy of its molecules. The faster the molecules of a substance move, the higher the kinetic free energy, and the higher the temperature. The slower the molecules motility, the lower the kinetic energy, and the lower the temperature. But at any temperature, the molecules don't all move at the aforementioned speed so temperature is actually a measure out of the boilerplate kinetic energy of the molecules of a substance.

   • These ideas apply to solids, liquids, and gases. The little balls in the simulation represent molecules and change color to aid visualize their speed and kinetic free energy. The slow ones are blue, the faster ones are purple or pink, and the fastest are red. Explicate also that private molecules change speed based on their collisions with other molecules. Molecules transfer their kinetic energy to other molecules through conduction. When a fast-moving molecule hits a slower-moving molecule, the slower molecule speeds up (and turns more red) and the faster molecule slows downward (and turns more blue).
   
   
   • Explicate that at any temperature, almost of the molecules are moving at almost the same speed and have about the same kinetic free energy, simply at that place are ever some that are moving slower and some that are moving faster. The temperature is actually a combination, or average, of the kinetic energy of the molecules. If you could place a thermometer in this simulation, information technology would be struck by molecules going at different speeds then it would register the average kinetic energy of the molecules.

   To add energy, start with "Cold" and then printing "Medium" and then "Hot".

   Ask students:

   What do yous detect near the molecules equally energy is added?

   As energy is added, more molecules are moving faster. There are more than pink and reddish molecules simply there are still some slower-moving blue ones.

   To remove free energy, starting time with "Hot" and then press "Medium" and then "Common cold".

   Inquire students:

   What do you observe most the molecules as free energy is removed?

   As energy is removed, more molecules are moving slower. There are more purple and blueish molecules, only a few all the same modify to pink.

9. Have students try ane or more extensions and utilise conduction to explain these common phenomena.

   Compare the actual temperature and how the temperature feels for unlike objects in the room.

   Ask students:

   Touch the metal part of your chair or desk-bound leg and so touch the cover of a textbook. Exercise these surfaces feel like they are the same or a different temperature?

   They should feel different.

   Why does the metal feel colder even though information technology is the same temperature as the cardboard?

   Tell students that even though the metallic feels colder, the metal and the cardboard are actually the aforementioned temperature. If students don't believe this, they can use a thermometer to accept the temperature of metal and paper-thin in the room. Later on beingness in the same room with the same air temperature, both surfaces should be at the same temperature.

   Show the animation Conducting Free energy to help answer the question about why metal feels colder than cardboard.

   Tell students to watch the motion of the molecules in the metal, cardboard, and in the finger.

   Explicate that the molecules in your finger are moving faster than the molecules in the room-temperature metallic. Therefore the energy from your finger is transferred to the metallic. Because metal is a good conductor, the energy is transferred abroad from the surface through the metallic. The molecules in your skin slow downward every bit your finger continues to lose free energy to the metal, so your finger feels cooler.

   Similar the metal, the molecules in your finger are moving faster than the molecules in the room-temperature cardboard. Energy is transferred from your finger to the surface of the cardboard. But because paper-thin is a poor usher, the energy is non easily transferred abroad from the surface through the cardboard. The molecules in your peel move at about the same speed. Because your finger does not lose much energy to the cardboard, your finger stays warm.

   Compare the bodily temperature and how the temperature feels for water and air.

   Take students use two thermometers to compare the temperature of room-temperature water and the temperature of the air. They should be about the same.

   Ask students:

   Put your finger in room-temperature water and another finger in the air. Exercise the water and the air experience like they are the aforementioned or a different temperature?

   The finger in the water should experience colder.

   Why does the water feel cooler even though it is the same temperature equally the air?

   Remind students that even though the water feels colder, the h2o and the air are really virtually the aforementioned temperature. Students should realize that water is better than air at conducting energy. Every bit energy is drawn more than rapidly abroad from your finger, your peel feels colder.

   Consider why cups of cold and hot water both come up to room-temperature.

   Take students remember about and explain the following situation:

   Let's say that y'all put a cup of cold water in one room and a cup of hot h2o in another room. Both rooms are at the same room-temperature. Why does the cold h2o go warmer and the hot h2o get cooler?

   In both cases, energy will move from an expanse of higher temperature to an area of lower temperature. So, the energy from room-temperature air will move into the cold water, which warms the h2o. And the free energy from the hot water will movement into the cooler air, which cools the water.

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Source: https://www.middleschoolchemistry.com/lessonplans/chapter2/lesson1

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