Quiz for Enthalpy

Q1: Enthalpy (H) is defined as:

A. H = U + PV B. H = U - PV C. H = PV D. H = U

Q2: In a constant pressure process, the heat exchanged is equal to:

A. Change in internal energy B. Change in enthalpy C. Work done D. Heat capacity

Q3: The standard enthalpy change of formation (ΔHf°) is the enthalpy change when:

A. One mole of a compound forms from its elements in standard states B. One mole of a compound decomposes C. Any reaction occurs D. Elements react at any conditions

Q4: Which process has negative enthalpy change?

A. Exothermic B. Endothermic C. Isothermal D. Adiabatic

Q5: Enthalpy is a:

A. State function B. Path function C. Variable D. None

Q6: Which unit is enthalpy commonly expressed in?

A. Joule B. Pascal C. Newton D. Watt

Q7: Hess’s law states that:

A. Total enthalpy change is independent of the pathway B. Total energy change depends on pathway C. Heat is not conserved D. Pressure is constant

Q8: Enthalpy of combustion is:

A. Heat change when one mole of substance burns completely B. Heat absorbed in melting C. Heat released during freezing D. Heat absorbed in vaporization

Q9: Which quantity is zero for elements in their standard states?

A. Enthalpy of formation B. Internal energy C. Heat capacity D. Entropy

Q10: The relation between enthalpy (H) and internal energy (U) is:

A. H = U + PV B. H = U - PV C. H = U x PV D. H = U / PV

Q11: If pressure and volume are constant, the change in enthalpy is equal to:

A. Heat added or removed B. Work done C. Internal energy change D. Entropy change

Q12: Which of the following is an extensive property?

A. Enthalpy B. Temperature C. Pressure D. Density

Q13: The heat capacity at constant pressure (Cp) is related to enthalpy as:

A. Cp = (dH/dT)p B. Cp = (dU/dT)p C. Cp = (dH/dV)p D. Cp = (dS/dT)p

Q14: Which of the following reactions will have positive ΔH?

A. Endothermic B. Exothermic C. Neutral D. None

Q15: Enthalpy change during phase transition at constant pressure is:

A. Equal to heat absorbed/released B. Equal to work done C. Zero D. Negative always

Q16: Standard enthalpy of neutralization involves:

A. Heat released when acid and base react to form water B. Heat absorbed on melting C. Heat required to vaporize D. Heat involved in ionization

Q17: Enthalpy is measured using:

A. Calorimeter B. Barometer C. Spectrometer D. Voltmeter

Q18: Which of the following is NOT true about enthalpy?

A. It is a state function B. It depends on path C. It depends on pressure D. It includes internal energy

Q19: The symbol ΔH represents:

A. Change in enthalpy B. Change in entropy C. Change in volume D. Change in temperature

Q20: In an endothermic reaction:

A. System absorbs heat B. System releases heat C. No heat change D. Heat exchange depends on volume