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Energy & Stoichiometry

Energy & Stoichiometry. Exothermic and Endothermic. HEAT. HEAT. Exothermic process – heat is released into the surroundings Exo = Exit Endothermic Process – heat is absorbed from the surroundings Endo = Into. Thermochemical Equations.

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Energy & Stoichiometry

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  1. Energy &Stoichiometry

  2. Exothermic and Endothermic HEAT HEAT • Exothermic process – heat is released into the surroundings • Exo = Exit • Endothermic Process – heat is absorbed from the surroundings • Endo = Into

  3. Thermochemical Equations • In a thermochemical equation, the energy of change for the reaction can be written as either a reactant or a product • Enthalpy: the heat content of a system at constant pressure (ΔH) • Endothermic (positive ΔH) 2NaHCO3 + 129kJ Na2CO3 + H2O + CO2 • Exothermic (negative ΔH) CaO + H2O Ca(OH)2 + 65.2kJ

  4. Exo 4 3 2 1 mol 10.00g Fe 1652 kJ =73.97 kJ of heat 4 mol Fe 55.85g Fe Write the thermochemical equation for the oxidation of Iron (III) if its ΔH= -1652 kJ Fe(s) + O2(g)→ Fe2O3(s) + 1652 kJ How much heat is evolved when 10.00g of Iron is reacted with excess oxygen?

  5. Endo 1 mol NaHCO3 50.0 g NaHCO3 129kJ 83.9 g NaHCO3 2mol NaHCO3 =38.4kJ of heat Write the thermochemical equation for the decomposition of sodium bicarbonate, with a ΔH = + 129 kJ: 2 NaHCO3 + 129kJ → Na2CO3(s) + H2O + CO2 How much heat is required to break down 50.0g of sodium bicarbonate?

  6. Exo 100 g CaO 1 mol CaO 65.2kJ 56.07 g CaO 1mol CaO =116kJ of heat Write the thermochemical equation for a single replacement of calcium oxide and water with a ΔH= - 65.2 kJ: CaO + H2O → Ca(OH)2 + 65.2kJ How much energy is released when 100 g of calcium oxide reacts?

  7. Endo 420kJ 1 mol O2 31.98 g O2 =218 gof O2 61.5 kJ 1mol O2 Write the thermochemical equation for the decomposition of magnesium oxide with a ΔH= + 61.5 kJ: 2MgO + 61.5 →2 Mg + O2 How many grams of oxygen are produced when magnesium oxide is decomposed by adding 420 kJ of Energy?

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