3. Enthalpy change is defined as __________ a. the energy that is transferred in

Question

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 P–V 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 °C)] a. 7.94 J/(g °C) d. 0.664 J/(g °C) b. 5.17 J/(g °C) e. 2.32 J/(g °C) c. 1.89 J/(g °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 °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. 34 kJ/mol d. 43 kJ/mol b. 54 kJ/mol e. 14 kJ/mol c. 17 kJ/mol

Explanation / Answer

-q gained by Alumina = q lost by H2O
q alumina + q H2O = 0
-(0.5 * 10^3 * s * (61.8 - 25)) = 0.25 * 10^3 * 4.18 * (61.8 - 95)
specific heat of alumina = 1.8855 J/g

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.