Name: _______________________________________
LAB: Conduction
Introduction: Where there is a difference in temperature between any two objects or regions in contact,
energy will be transferred from high potential to low potential by conduction. Conduction occurs as
rapidly moving or vibrating atoms and molecules interact with those in contact with them, transferring
some of their kinetic energy. Conduction is greater in solids because the closely spaced atoms within solids
helps to transfer energy between them by vibration. Liquids and especially gases have atoms spaced
further apart and are lower in density, which causes fewer collisions between atoms meaning less
conduction in these phases of matter.
Objective: You will be able to measure and explain heat flow by conduction from one region to another.
Hypothesis: Predict heating/cooling rate for each cup and why.
Vocabulary:
Conduction:
Rate of Change:
Calorimeter:
Conservation of Energy:
Procedure:
1.
2.
3.
4.
5.
You will use the calorimeter equipment as set up in the diagram below.
Fill one insulated cup with cold water and the other with boiling water. Quickly replace the lid
assembly for each.
When the temperature in the “hot” cup reaches its highest point, record this temperature under
Time 0 on your Report Sheet. At exactly the same time, your partner should read and record the
temperature of the “cold” cup.
Continue taking temperature readings for both cups at one minute intervals for a total of 20
minutes.
Graph the recorded data, drawing both curves on one set of axes. Use time for the horizontal axis.
Be sure to properly label each line.
Heat Transfer By Conduction
Graph
Discussion Questions:
1. At the start, which calorimeter had the most potential energy?
2.
Which calorimeter lost energy?
3.
Which calorimeter was a heat source?
4.
In which direction did the heat energy flow?
5.
Compare the amount of energy lost by one cup compared to the amount of energy gained by the
other cup.
6.
Explain the difference for the amount of energy lost by one cup and the amount of energy gained
by the other cup.
7.
How does your graph show that there was a change in the rate of heat lost or gained over time.
8.
If the system were left standing for 24 hours, what predictions could you make about the
temperatures of the cups?
9.
How could you modify the equipment used in the experiment to increase the rate from the hot cup
to the cold cup?
10. Explain why there is a change in the rate of energy exchange as time passes.
Conclusion: Discuss the relative rates of heating and cooling of each cup and explain how heat
energy is transferred from the water in one calorimeter to the water of the other calorimeter.
Reading Comprehension Read the portion of the article on Conduction below and answer the following
questions based on the reading. Use complete sentences.
HEAT SHIELD SOLUTION
http://www.heatshieldsolution.com/
Managing the temperature in a building always involves controlling heat transfer. Heat transfer or heat
exchange is the transition of thermal energy from hotter object or area to cooler object or area. Whenever
there is a difference in temperature across a given area (for example, inside and outside a building), heat
naturally flows from warm areas to colder area. Regardless of direction it seeks a balance until the
temperature is the same across the whole area. In the summer or hot climate area, high heat from roofs and
walls travels from outside to inside and in winter, heat flows from the inside of a building to the outside.
Heat transfer can never be stopped, it can only be slowed or reflect away. The purpose of insulation is to
impede this natural process. In hot weather, you want to stop heat from being transferred into the building,
and in cold weather you want to stop it from being transferred out.
Conduction is the transfer of the heat through a solid object, liquid or gas. In order for the heat to be
conducted, there should be physical contact between particles and some temperature difference. When one
part of an object is heated, the molecules within it vibrate against one another, begin to move faster and
more vigorously, when these molecules hit other molecules within the object they cause heat to be
transferred through the entire object. Substances that conduct heat readily are called conductors, while
substances that don't conduct heat readily are called insulators. Metal (e.g. copper, platinum, gold iron, etc)
is a good conductor of thermal energy, aluminum is a good insulator. Wood falls somewhere in between.
Conduction is greater in solids, where molecules are in constant contact.
As density decreases so does conduction. Therefore, fluids (and especially gases) are less conductive. This
is due to the large distance between atoms in a gas, fewer collision between atoms means less conduction.
Conductivity of gases increases with temperature.
One way that heat can escape from your house is by conduction through the walls, ceilings, and windows.
Most walls and ceilings contain material to stop this heat conduction called insulation. There are many
types of insulation, depending on the location in the house and the degree of insulation that is desired. One
popular measure of the effectiveness of insulation is called the "R" factor. The R factor is a measure of the
resistance of the insulation to the transfer of heat. The higher the R factor, the more resistance, and the less
heat that is transferred. The materials and labor to install insulation cost money, so depending on the size
and location of the house, there is an R factor that is the most cost efficient. Most older homes were built
when the cost of energy was lower and the insulation was more expensive for the same R factor rating.
Therefore, it may save you both energy and money to invest in more insulation in your walls, roof or
ceilings.
The same concept of insulation applies to windows. Typically, the "insulation" that is used is air, since
regular insulation is a bit hard to see through. The air is trapped between two panes of glass. These double
paned insulated windows significantly decrease the loss of heat through the windows.
1.
What do you think the word “impede” means in the statement from the article that says “the
purpose of insulation is to impede this process”?
2.
What has to be true for conduction to occur?
3.
What makes something a good conductor instead of a good insulator?
4.
What’s better (more effective), insulation with an R-30 rating or an R-15 rating? Explain your
answer.
5.
A double pane window uses argon, and a second uses a vacuum (no air or gas at all). Which
window is a better insulator and why?