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Clicker Question Calculate E for a system that releases 28 J of heat while 63 J of work is done on it. a) -35 J b) -91 J c) 35 J d) 91 J

Clicker Question Use the following data for methanol (CH3OH):   ΔHvaporization = 35.3 kJ/mol at 64.7°C Determine ΔE (kJ/mol) for methanol vaporizing at 64.7°C. a) 32.5 b) 35.3 c) –35.3 d) 38.1 e) –38.1

Determining Hrxn Since H = qp, determine the heat given off or required at constant pressure by measuring temperatures. This is termed calorimetry. Since energy is conserved, we can often determine Hrxn for one reaction given values of Hrxn for others. Uses the principle in Hess’s Law. Use standard enthalpies of formations for reactants and products (we have tables of these).

A Coffee-Cup Calorimeter Made of Two Styrofoam Cups

Clicker Question A 25.0 g sample of copper (c= 0.385 J/gC) is placed in a boiling water bath until the temperature of the metal is 100.0C. The metal is quickly transferred to 100.0 g of water at 25.0C in a calorimeter (specific heat capacity of water = 4.18 J/gC). Determine the final temperature of the water in the calorimeter.   a) 22.2°C b) 23.2°C c) 25.9°C d) 26.7°C e) 27.8°C