SCH4U - Unit 3 - Version C - SCH4U Grade 12 University Chemistry Lesson 9 Thermochemistry SCH4U Chemistry Unit 3 Introduction Unit 3 Rates of Reaction

SCH4U - Unit 3 - Version C - SCH4U Grade 12 University...

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SCH4U Grade 12 University Chemistry Lesson 9 – Thermochemistry
SCH4U – Chemistry Unit 3 - Introduction Copyright © 2008, Durham Continuing Education Page 2 of 70 Unit 3: Rates of Reaction Energy transformations take place continually inside our bodies and in the world around us. For example, you transform the food you eat into useable cellular energy or adenosine triphosphate (ATP). Machines such as automobiles and power tools convert fuel into mechanical energy. In this unit you will learn more about energy transformations including the factors that affect reaction rate, and their kinetics. Overall Expectations demonstrate an understanding of the energy transformations and kinetics of chemical changes; determine energy changes for physical and chemical processes and rates of reaction, demonstrate an understanding of the dependence of chemical technologies and processes on the energetics of chemical reactions.
SCH4U – Chemistry Lesson 9 Copyright © 2008, Durham Continuing Education Page 3 of 70 Lesson 9: Thermochemistry Heat transformations take place everyday in both living organisms and machines. Cars, for example, convert gasoline into energy to propel the car forward. Heat is also lost in the process. In living organisms, the process of cellular respiration converts simple sugars into cellular energy, carbon dioxide, and water. Again, heat is lost in the process. The study of heat transformation is called Thermochemistry, and it will be the focus of this lesson. What You Will Learn After completing this lesson, you will; write thermochemical equations, expressing the energy change as a H value or as a heat term in the equation; determine heat of reaction, and use the data obtained to calculate the enthalpy change for a reaction compare the energy changes resulting from physical change, chemical reactions, and nuclear reactions (fission and fusion); Thermochemistry Thermochemistry is the study of energy changes involved in chemical reactions. These changes can be physical (i.e. melting ice,) chemical (rusting iron) or nuclear (nuclear fusion reactions in the Sun). All energy transformations are governed by the 1 st Law of Thermodynamics , which states that the total energy of the universe is constant. Thermodynamics Terms There are a set of terms that are necessary to understand when discussing thermodynamics. They are summarized following: Thermal energy : The energy available from a substance as a result of its motion of its molecules. For example, when you burn your foods, you break down sugars into carbon dioxide, water, ATP and thermal energy (heat). The SI unit for measuring work and all forms of energy is the Joule (J). Chemical system : The set of reactants and products undergoing energy transformations. Chemical systems can be open (energy and matter can move in or out), closed (only energy can move in or out), or isolated (neither energy or matter can move in or out)
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