1. Thermochemistry

2. C.11A Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. Supporting Standard http://www.teachertu be.com/viewVideo. php?video_id=1278 07

3. Thermochemistry C.11B Understand the law of conservation of energy and the processes of heat transfer. Supporting Standard C.11C Use thermochemical equations to calculate energy changes that occur in chemical reactions and classify reactions as exothermic or endothermic. Readiness Standard

4. Thermochemistry C.11D Perform calculations involving heat, mass, temperature change, and specific heat. Supporting Standard C.11E Use calorimetry to calculate the heat of a chemical process. Supporting Standard

5. Vocabulary of Instruction: energy kinetic energy potential energy thermal energy specific heat law of conservation of energy phase change heat transfer calorimetry

6. Key Understandings and Guiding Questions: Energy is conserved when heat is transferred. What is the law of conservation of energy? What is the difference between heat and temperature? What are the three types of energy transfer? List the forms of energy you know about. What is an example for each? How is a calorimeter used to measure energy transfer?

7. Energy Energy is the capacity to do work. Work is defined as force moving through a distance. In chemistry we consider the gas pressure against a piston moving it upward as work. Energy in motion is called ____. This refers to atoms and molecules moving in gases, liquids, and solids. What is the other type of energy?

8. Forms of Energy Light/Heat(Thermal)---Radiant-from electromagnetic waves Electricity-from flow of electric charges Magnetism-from alignment of charged particles which causes attractions or repulsions Mechanical-from movement of objects Chemical-energy stored in bonds Nuclear-energy stored in the nucleus Sound-from vibrations

9. Energy We cannot see energy, only its effects. Heat is the measure of the total amount of kinetic energy in a system. It is measured in joules or calories. It is measured with a calorimeter.

10. Energy Temperature is a measure of the effects of heat. It measures the average kinetic energy of a system. It is measured in o C or K. It is measured with a thermometer.

11. Energy Consider two beakers of water. One has 100 g of water at 80 o C. One has 100 g of water at 20 o C. Which one has more mass? Which one has more energy? Which one has the greater kinetic energy? What will happen if we pour the two together into a third beaker?

12. Energy What will be the mass of the water in the third beaker? What will be the temperature of the water in the third beaker? Did the cooler water cool the warm water or did the warmer water warm the cool water? In other words, which way did the heat flow?

13. Heat Flow Energy flows from a warmer object to a cooler one, never the reverse. There really isn’t such a thing as cold; there is just a lack of heat. The heat of a closed system is maintained (not lost to surroundings). In fact, those are the only two parts to the universe---systems and surroundings. If energy is lost by the system, it is gained by the surroundings and vice versa.

14. Methods of Heat Transfer Convection Conduction Radiation

15. Law of Conservation of Energy Energy is never lost or gained, only transferred or transformed. Heat lost = Heat gained q = m x C x ∆t where q is in joules or calories, m is in grams, C is the specific heat, and t is in Celsius.

16. Hess’ Law of Constant Heat Summation The sum of the heats of formation of the products minus the sum of the heats of formation of the reactants equals the heat of reaction. The heat of formation is the amount of energy needed to make a compound from its elements.

17. Gibb’s Free Energy Gibb’s free energy tells the amount of useful work that can be done by a system. Because it is work done by a system, it is going out of the system and so is given a negative sign if the reaction is spontaneous. ∆G = ∆H-T∆S where G is Gibb’s free energy, H is the enthalpy of reaction and S is the entropy of the reaction. T is in Kelvins.

18. Gibb’s Free Energy Entropy is the randomness of a system. More randomness is better. Gases are more random than liquids which are more random than solids.