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Energy & Heat

Energy & Heat. Crystal Gray Joshua Osborne Samuel Anum Maurice Torrance. What is energy?. Energy - the ability to do work or produce heat

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Energy & Heat

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  1. Energy&Heat Crystal Gray Joshua Osborne Samuel Anum Maurice Torrance

  2. What is energy? • Energy - the ability to do work or produce heat ~Potential energy – energy due to the composition of an object (type of atoms, number and type of chemical bonds joining the atoms, and the arrangement) ~Kinetic energy is energy in motion *As temp. increases, the motion of submicroscopic particles increase As temp. decreases, the motion of submicroscopic particles decrease

  3. Law of Conservation of Energyaka1st Law of Thermodynamics • Law states that in any chemical reaction / physical process, energy can be converted from one form to another, but its neither created nor destroyed

  4. What is heat? • Heat – form of energy that flows from a warmer object to a cooler object • Represented by q • Measure Heat with calories. ~calorie (cal) – amount of heat req. to raise the temp. of 1g of pure water by 1°C ~Calorie (nutritional) – equals 1,000 calories or 1 kilocalorie (kcal) ~Joule (J) – SI unit for heat and energy

  5. 1 J = 0.2390 cal 1cal = 4.184 J 1Calorie = 1 kcal Conversion Factories

  6. Specific Heat • The specific heat of any substance is the amount of heat required to raise the temp.of one gram of that substance by one degree Celsius. • Different substances have different compositions. • Each substance has its own specific heat.

  7. Calculating heat absorbed • Equation for calculating heat: q= c x m x T. • q= The heat absorbed or released • c= The specific heat of the substance. • m= The mass of the sample in grams. • T= The change in temperature in degrees Celsius, or T(final) – T(initial).

  8. Calculating heat released • Substances can both absorb and release heat. • The same equation for q can be used to calculate the energy released by substances when they cool off.

  9. Using the sun’s energy • Radiation from the sun could supply all the energy needs of the world and reduce or eliminate the use of carbon dioxide-producing fuels, but several factors have delayed the development of solar technologies.

  10. Chapter 15.2 pt.2 Maurice Torrance

  11. Heat • Main Idea: The enthalpy charge for a reaction is the enthalpy of the products minus of the reactants. • Calorimeter: an insulated device used for measuring the amount of heat absorbed or released during a chemical or physical process. • You determine specific heat by using q=(c)(m)deltaT

  12. Chemical Energy and the universe • Thermochemistry: The study of heat change that accompany chemical reaction and phase changes • The system is the specific heat part of the universe • Everything in the universe other than the system is considered surrounding. • Universe=system+surroundings

  13. Enthalpy • To more easily measure and study the energy changes that accompany reactions, chemists defined a property called enthalpy • Enthalpy is the heat content of a system • The equation to find enthalpy is H = Hfinal –Hintial or H= Hproducts - Hreactants

  14. How to spot signs of enthalpy of reaction • In an exothermic reaction enthalpy changes are always negative because the Hproducts is less thanHreactants • In an endothermic reaction enthalpy changes are always positive because the Hproducts are more than the Hreactants • Always remember that H = q as long as the pressure is constant

  15. Enthalpy Diagram

  16. Interactive Website • http://sciencereviewgames.com/srg/games/hs.php?id=31

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