Chapter 5: QCYL (page 257)
How much heat is produced by the combustion of 125 g of acetylene?
125 g of acetylene produces 6.25 kJ of heat.
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Calculate โH for the reaction described by the equation. (Hint: use the value for the approximate amount of heat absorbed by the reaction that you calculated in a previous exercise.)
Ba(OH)2. 8H2O(s) + 2NH4SCN(aq) โ Ba(SCN)2(aq) + 2NH3(aq) + 10H2O(l)
From the molar heats of formation in Appendix G, determine how much heat is required to evaporate one mole of water:\({{\bf{H}}_{\bf{2}}}{\bf{O}}\left( {\bf{l}} \right) \to {{\bf{H}}_{\bf{2}}}{\bf{O}}\left( {\bf{g}} \right)\)
The addition of 3.15g of Ba(OH)2.8H2O to a solution of 1.52g of NH4SCN in 100g of water in a calorimeter caused the temperature to fall by 3.1หC. Assuming the specific heat of the solution and products is 4.20J/gหC, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation:
Ba(OH)2.8H2O(s) + 2NH4SCN (aq) -------> Ba(SCN)2(aq) + 2NH3(aq) + 10H2O(l)
Dissolving 3.0 g of CaCl2(s) in 150.0 g of water in a calorimeter (Figure 5.12) at 22.4ยฐC causes the temperature to rise to 25.8ยฐC. What is the approximate amount of heat involved in the dissolution, assuming the heat capacity of the resulting solution is 4.18 J/gยฐC? Is the reaction exothermic or endothermic?
Before the introduction of chlorofluorocarbons, sulfur dioxide (enthalpy of vaporization, 6.00 kcal/mol) was used in household refrigerators. What mass of \({\bf{S}}{{\bf{O}}_{\bf{2}}}\)must be evaporated to remove as much heat as evaporation of 1.00 kg of \({\bf{CC}}{{\bf{l}}_{\bf{2}}}{{\bf{F}}_{\bf{2}}}\) (enthalpy of vaporization is 17.4 kJ/mol)?
The vaporization reactions for \({\bf{S}}{{\bf{O}}_{\bf{2}}}\)and \({\bf{CC}}{{\bf{l}}_{\bf{2}}}{{\bf{F}}_{\bf{2}}}\)are\({\bf{S}}{{\bf{O}}_{\bf{2}}}{\bf{(l)}} \to {\bf{S}}{{\bf{O}}_{\bf{2}}}{\bf{(g) and CC}}{{\bf{l}}_{\bf{2}}}{\bf{F(l) }} \to {\bf{CC}}{{\bf{l}}_{\bf{2}}}{{\bf{F}}_{\bf{2}}}{\bf{(g)}}\), respectively.
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