1. Chapter 9 Heat

2. Temperature  Temperature is proportional to the kinetic energy of atoms and molecules.  Internal energy is the energy of a substance due to the random motions of its component particles and equal to the total energy of those particles. Internal energy Internal energy

3. All molecules have 3 types of motion: Translational movement – forward or backward movement Translational movement – forward or backward movement

4. Rotational movement – spinning motion Rotational movement – spinning motion

5.  Vibration – small, fast movements back and forth

6. Temperature is decided by how much a molecule or atom bounces around a container and hit another molecule and atom. Which type of movement is this? Temperature is decided by how much a molecule or atom bounces around a container and hit another molecule and atom. Which type of movement is this? Translational Translational Temperature of an object is dependent upon translational movement only. Temperature of an object is dependent upon translational movement only.

7.  Thermal equilibrium is the state in which two bodies in physical contact with each other have identical temperatures.  Matter expands as its temperature increases. expands

8. Temperature Conversion Temperature Conversion  Fahrenheit Temperature = (9/5 x Celsius Temperature) +32  T f = (9/5T c ) +32  Kelvin Temperature = Celsius temperature + 273.15  T = T c + 273.15

9. Defining Heat and Energy Defining Heat and Energy  Energy that is transferred is defined as heat.  Heat has the units of energy (Joules, J)  Heat is indicated by the symbol Q.

10. Conservation  Total Energy is conserved.  The change in potential energy + the change in kinetic energy + the change in internal energy = 0  ∆PE + ∆KE + ∆U = 0

11. Specific Heat Capacity Specific Heat Capacity  Each substance has it’s own value for the amount of energy it needs to change the temperature of 1 kg of a substance by 1 0 C. This is value is known as specific heat.  Specific Heat = c p  Units are J/Kg 0 C

12. Specific Heat Equation  Specific Heat = energy transferred as heat / (mass x change in temperature)  c p = Q / (m ∆T)

13. Calorimetry  Since the specific heat of water is known to be 4186 J/Kg 0 C, we can use an approach called calorimetry to determine a 2 nd object’s specific heat.  We place a heated unknown object in an insulated container of cool water.  Since energy is conserved, the energy the substance gives up must equal the energy absorbed by the water.

14. Calorimetry Equation  Specific heat of water x mass of water x change in temperature of water = specific heat of unknown x mass of unknown x change in temperature of uknown  c p, w m w ∆T w = c p, x m x ∆T x

15. Phase Change Phase Change  Phase changes involve potential energy between particles.  Potential energy is present among a collection of particles in a solid or a liquid in the form of attractive bonds.  The potential energy increases with increasing atomic separation from the equilibrium position. This resembles a spring.  If the particles are far enough apart, the bonds between them break and release kinetic energy.

16. Latent Heat Latent Heat  Latent heat is the energy per unit mass that is transferred during a phase change of a substance.  Units of Latent Heat = J/Kg  Energy transferred as heat during a phase change = mass x latent heat  Q = mL

17. Thermal Conduction Thermal Conduction  Thermal conduction is the process by which energy is transferred by heat through a material between two points of different temperatures.  As an object is heated, the atoms nearest the heat vibrate with greater energy. These vibrating atoms jostle their less energetic neighbors and transfer some of their energy. Gradually, atoms farther away from the heat are also vibrated and gain energy.

18. Convection  Convection involves the displacement of cold matter by hotter matter, such as when hot air over a flame rises upward.  This method does not use heat alone but uses pressure and buoyancy also.

19. Electromagnetic Radiation Electromagnetic Radiation  Electromagnetic radiation transfers energy through wavelengths.  This form does not involve the transfer of matter like conduction and convection.

20. Assignment  Unit 9 Worksheet