chapter6_ws_key

Chapter6_ws_key - Chem127 Dr.Abel Chapter 6 Worksheet 1 What are the two main components of internal energy of a substance What are the symbols for

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Chem 127 Dr. Abel Chapter 6 Worksheet 1. What are the two main components of internal energy of a substance? What are the symbols for internal energy and its two components? Internal energy (E) is composed Heat (q) and work (w) 2. A system which undergoes an adiabatic change is one in which no heat is transferred. For an adiabatic change that does work on its surroundings, indicate if q, w and Δ E for such a process should be positive, negative, or equal to zero. Explain. q = 0 (no heat is exchanged), w = - (energy lost from the system as work), Δ E = - ( Δ E = q + w) 3. For each of the following, define the system and the surroundings, and indicate the direction of heat transfer. a) Natural gas is burned in a gas furnace in your home. System – natural gas burning Surroundings – everything else (home and the entire rest of the universe) Heat transferred from the system to surroundings (-q) b) Water drops, sitting on your skin after a dip in the pool, evaporate. System – water drops Surroundings – everything else Heat transferred from the surroundings to system (+q) (this is why your skin – part of the surroundings – feels cool when sweat or water evaporates) 4. Does a negative Δ H rxn mean that the heat of reaction can be thought of as a reactant or a product? – Heat is released, so it is a product 5. For the reaction CO (g) + NO (g) ----> CO 2 (g) + 1/2 N 2 (g) Δ H = -373.3 kJ a) Which should go at higher energy on an energy level or an enthalpy diagram, the products or the reactants? Draw an energy level diagram that illustrates this reaction. CO (g) + NO (g) H Δ H = -373.3 kJ, heat released CO 2 (g) + 1/2 N 2 (g) b) Which has stronger bonds, the products or reactants? Explain. The products have stronger bonds. The products are lower in energy and more stable. 6. Does the potential energy increase or decrease in the following processes? a. H H bond breaks, separating two atoms with an attractive force, _ increase _ b. F F bond breaks, separating two atoms with an attractive force, __ increase _ c. 2 H F bonds form, joining two atoms with an attractive force,___ decrease _____
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This note was uploaded on 06/08/2008 for the course CHEM 127 taught by Professor Able during the Spring '08 term at Cal Poly.

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Chapter6_ws_key - Chem127 Dr.Abel Chapter 6 Worksheet 1 What are the two main components of internal energy of a substance What are the symbols for

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