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Unit 1: Basic Concepts of Chemistry. Energy and Chemical Reactions Part II. Energy and Chemical Reactions. Energy transfer of physical and chemical processes. Physical processes that have energy transfers:. Chemical processes that have energy transfers:.
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Unit 1: Basic Concepts of Chemistry Energy and Chemical Reactions Part II
Energy and Chemical Reactions Energy transfer of physical and chemical processes Physical processes that have energy transfers: Chemical processes that have energy transfers: We call this transferred energy … Enthalpy, H
Energy and Chemical Reactions Enthalpy changes for chemical reactions Almost all chemical reactions either release or absorb heat Reactant Reactant Product + HEAT Reactant Reactant Product + HEAT
Energy and Chemical Reactions Enthalpy Changes for Chemical Reactions Standard Reaction Enthalpies, ∆rHo The decomposition of water vapor … Sucrose, C12H22O12 can be oxidized to CO2 and H2O and the enthalpy change can be measured under constant pressure. 2C12H22O12+ 23O2 24CO2+ 22H2O ∆rHo= -5645 KJ/mol What is the energy transferred as heat by burning 5.0 g sucrose?
Energy and Chemical Reactions Calculating Enthalpies of Reaction, ∆rHo Standard Enthalpy of Formation Values, ∆fHo An Enthalpy of Formation is just a special, standardized type of reaction enthalpy … ∆rHo= ∑ ∆fHo(products) -∑∆fHo(reactants)
Energy and Chemical Reactions Calculating Enthalpies of Reaction, ∆rHo Calculate the heat of reaction for each of the following reactions: 2 CO(g) + O2(g) ---> 2 CO2(g) • 2 H2S(g) + 3 O2(g) ---> 2 H2O(l) + 2 SO2(g) • If 2 Liters of hydrogen sulfide gas reacts at STP, how much heat is transferred?
