In the laboratory a “coffee cup” calorimeter or constant pressurecalorimeter is frequently used to determine the specific heat of a solid orto measure the energy of a solution phase reaction.Since the cup itself can absorb energy a separate experiment is needed todetermine the heat capacity of the calorimeter. This is knownas calibrating the calorimeter and the value determined is calledthecalorimeter constant.One way to do this is to use a common metal of known heat capacity. Inthe laboratory a student heats98.15 grams of nickel to 98.47 °C and thendrops it into a cup containing 80.82 grams of water at24.52 °C. Shemeasures the final temperature to be 32.92 °C.Using the accepted value for the specific heat of nickel (See the Referencestool) calculate the calorimeter constant.Calorimeter Constant =J/°C.A bomb calorimeter or a constant volumecalorimeter is a device often used to determine theheat of combustion of fuels and the energy contentof foods.In an experiment a 0.6254 g sample of diphenylphthalate (C20H14O4) is burned completely in abomb calorimeter. The calorimeter is surroundedby 1.255×103 g of water. During the combustionthe temperature increases from 28.22 to 31.33°C.The heat capacity of water is 4.184 J g-1°C-1.The heat capacity of the calorimeter wasdetermined in a previous experiment tobe 901.1 J/°C.Assuming that no energy is lost to thesurroundings calculate the molar heat ofcombustion of diphenyl phthalate based on thesedata.C20H14O4(s) (43/2) O2(g) 20 CO2(g) EnergyMolar Heat of Combustion =7 H2O(l)kJ/mol A bomb calorimeter or a constant volumecalorimeter is a device often used to determine theheat of combustion of fuels and the energy contentof foods.In an experiment a 0.3943 g sampleof biphenyl (C12H10) is burned completely in abomb calorimeter. The calorimeter is surroundedby 1.021×103 g of water. During the combustionthe temperature increases from 26.87 to 29.81 °C.The heat capacity of water is 4.184 J g-1°C-1.The heat capacity of the calorimeter wasdetermined in a previous experiment tobe 944.3 J/°C.Assuming that no energy is lost to thesurroundings calculate the molar heat ofcombustion of biphenyl based on these data.C12H10(s) (29/2) O2(g) 12 CO2(g) Energy5 H2O(l)Molar Heat of Combustion =kJ/molA scientist measures the standard enthalpy change for the following reaction to be -65.4 kJ :S(s rhombic) 2 CO(g)SO2(g) 2 C(s graphite)Based on this value and the standard enthalpies of formation for the other substances the standardenthalpy of formation of CO(g) iskJ/mol.A scientist measures the standard enthalpy change for the following reaction to be 79.6 kJ:NH4Cl(aq)NH3(g) HCl(aq) Based on this value and the standard enthalpies of formation for the other substances the standardenthalpy of formation of HCl(aq)iskJ/mol.
