1. Energy

2. What is Energy? Energy is the ability to do work or produce heat Energy exists in two basic forms –Potential Energy: energy due to the composition or position of an object –Kinetic Energy: Energy of motion

3. The law of conservation… The law of conservation of energy states: Any chemical reaction or physical process, energy can be converted from on form to another, but it is neither created nor destroyed.

4. Chemical Potential Energy Chemical Potential Energy: is energy stored in a substance because of it’s composition. Example: –Octane (C 8 H 18 ) is a component of gasoline –When gasoline burns, some of octane’s stored energy is converted to work in moving the parts of a car.

5. Heat Heat is energy that is in the process of flowing from a warmer object to a cooler object. –Loss of heat temperature decreases –Gain of heat temperature increases

6. Measuring Heat The flow of energy and the resulting change in temperature are clues to how heat is measured. Calorie: the amount of heat required to raise the temperature of one gram of pure water by one degree Celsius.

7. How does this relate to calories in food? When your body breaks down sugars and fats to form carbon dioxide and water, these exothermic reactions generate heat that can be measures in Calories. Calories for food content are capitalized because they represent kilocalories (kcal). 1 kcal = 1000 cal

8. Joule is not a Gem 1 Joule = 0.2390 cal 1 cal = 4.184 Joules

9. Specific Heat Specific Heat: of any substance is the amount of heat required to raise the temperature of one gram of any substance by one degree Celsius. Unit Joules Gram °C SubstanceSpecific Heat J/(g *C) Water (liquid)4.184 Water (ice)2.03 Water (steam)2.01 Aluminum0.897 Ethanol (liquid) 2.44

10. Equation Heat absorbed or released depends on the specific heat of a substance as well as the mass. q = c x m x ∆T q = heat absorbed or released c = the specific heat M = mass ∆T = change in temperature

11. Example If the temperature of 34.4 g of ethanol increases from 25.0 °C to 78.8°C, how much heat has been absorbed by the ethanol c = 2.44 J/(g*C)