1)A calorimeter contains 24.0 Solution q = Cs x m x dT = -(4.18J/gC)(24.0g+1.6g)

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Explanation / Answer

q = Cs x m x dT = -(4.18J/gC)(24.0g+1.6g)(26.5C-15) = -1230.59J Now divide by moles: 1.60g/62.0g = 0.0258 mol = -47697.28 J/mol = x 1KJ / 1000J =- 47.69 KJ/mol C2H4 + H20 --> C2H5O formation enthalpy of ethane -> –83.8 kJ/mol formation enthalpy of water -> -291.83 kJ/mol formation enthalpy of ethanol -> –277.7 kJ/mol Since the equation is properly balanced, then the enthalpy change is just -277 + 291 + 83 = 97 So, the enthalpy of the reaction is just 97 kJ/mol the following bonds are broken C-H bonds = 5 * 413 = 2065 kJ/mol C-C bonds = 1 * 348 = 348 kJ/mol C-O bonds = 1 * 360 = 360 kJ/mol O-H bonds = 1 * 366 = 366 kJ/mol O=O bonds = 3 *498 = 1494 kJ/mol Bond broken Energy input = 4633 kJ/mol The following bonds are formed C=O bonds = -4 * 799 = -3196 kJ/mol O-H bonds = -6 * 366 = -2196 kJ/mol Bond formed Energy output = -5392 kJ/mol delta H = 4633 - 5392 = -759 kJ/mol This is different than the value determined by enthalpy because of the use of average bond energies which are obtained by bonds of gaseous state molecules.

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