3. Enthalpy change is defined as __________ a. the energy that is transferred into or out of a system when the pressure is constant and only PâV work is done. b. the change in internal energy of a system when the pressure is constant. c. the change in internal energy of a system when the volume is constant. d. the energy that is transferred into or out of a system when the pressure is constant and no work is done. e. the change in internal energy of a system when the pressure is constant and no work is done.
4. In an experiment, 0.250 kg water at 95.0°C is quickly transferred to a 0.500 kg alumina crucible at 25°C. The final temperature comes to 61.8°C. What is the approximate specific heat capacity of alumina? [cp(water) = 4.18 J/(g ï °C)] a. 7.94 J/(g ï °C) d. 0.664 J/(g ï °C) b. 5.17 J/(g ï °C) e. 2.32 J/(g ï °C) c. 1.89 J/(g ï °C)
5. When a 13.0 g sample of NaOH(s) dissolves in 400.0 mL of water to produce 413.0 g of solution in a constant pressure calorimeter, the temperature of the water and reaction vessel changes from 22.6°C to 30.6°C. Assume that the specific heat capacity of the solution is 4.2 J/(g ï °C), and that the heat capacity of the reaction vessel is 1.00 J/°C. What is the molar enthalpy of solution of the sodium hydroxide (40.00 g/mol)? a. ï34 kJ/mol d. ï43 kJ/mol b. ï54 kJ/mol e. ï14 kJ/mol c. ï17 kJ/mol