Moving Thermal Energy
1. Differentiate between conduction, convection, and radiation. 2 GOALS Intro Clip 1. Differentiate between conduction, convection, and radiation. 5. Explain molecular motion as it relates to thermal energy changes in terms of conduction, convection, and radiation. 2. Explain common examples, such as ice in a soda, to show the direction of energy flow. 6. Analyze and interpret specific heat data to justify the selection of a material for a practical application (e.g.,insulators & cooking vessels). 7. Plan and carry out investigations to describe how molecular motion relates to thermal energy changes in terms of conduction, convection, and radiation. 3. Use a calorimeter 4. Determine the heat capacity of a substance using mass, specific heat, and temperature.
Temperature and Heat Temperature is the measurement of the avg. KE of the molecules in a material. Heat is the transfer of KE from one material to another. Clip
Heat flows from WARMER to COLDER!
Eureka:Temperature VS Heat
Conduction The transfer of thermal energy in solids. Clip The transfer of thermal energy in solids. Materials must be in direct contact with each other! Ex: Heating of the bottom of a pot on stove.
Convection The matter actually moves from one place to another. clip Transfer of thermal energy in liquids and gases. The matter actually moves from one place to another.
Radiation Clip Transfer of thermal energy by electromagnetic waves (we’ll discuses these more later) Transferring energy through space...NO MATTER IS REQUIRED!
Eureka: conduction, convection, radiation
REVIEW Clip
Which would heat up faster? The aluminum or the plastic? Specific Heat Adding Energy to a material Causes the… Temperature to go up. Taking energy away from a substance causes the temp. to… Go down! Which would heat up faster? The aluminum or the plastic? Specific means “certain”
Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? OR maybe that the ocean is cooler than the hot sand? Why? The sun has been beating down on (delivering energy to) both of them for the same amount of time.....same amount of energy. It takes more thermal energy to raise the temperature of water that it does the cement!
Water absorbs a lot of heat energy before its temperature changes while sand needs little heat energy before its temperature increases.
Specific Heat The amount of energy required to raise the temperature of a material (substance). It takes different amts of energy to make the same temp change in different substances. We call the amt required: Specific Heat!
Specific Heat of water The Cp is high because H2O mols. form strong bonds w/each other. It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP).
Example: Specific Heat of Water Cp = 4,184 Joules of energy to raise the temperature of 1kg 1°C. video clip Why Cp? Cp Stands for “Heat Capacity”
Calculating Specific Heat The Greek letter Δ means “change in”
Can you get a negative “Q” Q =m x Cp x Δt Yes. If the object is LOSING heat.
EXAMPLE : What amount of heat is required to raise the temperature of 85.9 g of water by 7C? The specific heat of water is 4.184 J/gC. Mass = 85.9g Q = ? Δt = 7° Cp = 4.184 J/g-C? Q =m x Cp x Δt Q= (85.9kg)(4.184 J/g-C)(7°C) Q= 2515.8 J (WHAT DOES THAT MEAN?)
EOCT QUESTION
A by traveling through space as waves B by the movement of fluids C by the expansion of gases D by contact between particles
Show work on bottom of page 2 (in the blank space). A copper ornament has a mass of 0.0693 kg and changes from a temperature of 20.0°C to 27.4ºC. How much heat energy did it gain? Show work on bottom of page 2 (in the blank space).
Specific Heat Lab Thermometer Lg Testtube 5 ml H2O Calorimeter w/PC
Calorimeter
Eureka: Conduction
Eureka: Convection