# Physical Chemistry Questions and Answers – Real Gases, Isotherms and Critical Conditions

This set of Physical Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Real Gases, Isotherms and Critical Conditions”.

1. What is the difference between the energy of resonance hybrid and resonating structure?
a) Resonance hybrid have lower energy
b) Resonance hybrid have higher energy
c) Resonance hybrid is equal to resonating structure
d) There is no difference

Explanation: Difference between the energy of resonance hybrid and resonating structure is that resonating hybrid have lower energy because stabilized by resonance.

2. What is Integral enthalpy of a solution?
a) Enthalpy change when one mole of the solute is dissolved in a definite quantity of solvent to produce a solution
b) Enthalpy change when one mole of a compound combines with the requisite amount of oxygen to give products in stable forms
c) Average of enthalpies required to dissociate the bond
d) It is the change of standard enthalpy when one mole of the compound is formed starting from the requisite number of elements in their stable state of aggregation

Explanation: The Integral enthalpy of a solution at the given concentration is the enthalpy change when one mole of the solute is dissolved in a definite quantity of solvent to produce a solution of the desired concentration. It often expressed in kJ/mole.

3. Integral enthalpy of a solution depends upon ____________
a) Viscosity
b) Temperature of the solute
c) Density
d) Nature of solute

Explanation: Integral enthalpy of a solution depends upon the nature of the solute and the concentration in the final solution. It is often expressed in kJ/mole.

4. Born Haber’s cycle used to calculate lattice energy.
a) False
b) True

Explanation: Born Haber cycle is used to analyze reaction energies. It is used to calculate lattice energy, which cannot be measured directly.

5. ΔHf = V + ½ B + IEM – EAX + UL. What is V in this equation?
a) Enthalpy of sublimation
b) Bond energy
c) Ionization energy
d) Electron affinity

Explanation: V is the enthalpy of sublimation which defined as the heat required to change one mole of the substance from solid to a gaseous state at STP.

6. What is lattice enthalpy?
a) Enthalpy change required in the formation of an ionic compound from gaseous ions
b) It is a state of species at specified conditions
c) A reaction which forms a single compound from its constituent elements
d) It is the average of enthalpies required to dissociate the bond

Explanation: It is defined as the enthalpy change required in the formation of an ionic compound from gaseous ions or it is the energy to break the ionic compounds into gaseous ions.

7. What is the enthalpy of hydration?
a) It is the measure of bond strength in the chemical bond
b) Energy released when new bonds are made between ions and water molecules
c) Power required for the utilization of physical sources
d) Internal energy per unit mass

Explanation: Enthalpy of hydration is used in two ways:
1. Enthalpy of hydration of anhydrous o partially hydrated salts.
2. The enthalpy change when it combines with a requisite amount of water to form a salt.

8. What is the enthalpy of neutralization?
a) Enthalpy of hydration of anhydrous o partially hydrated salts
b) Heat released when one-gram equivalent of an acid is neutralized by one-gram equivalent to base
c) Energy released when new bonds are made between ions and water molecules
d) It is the measure of bond strength in the chemical bond

Explanation: Enthalpy of neutralization is defined as the amount of heat released in the formation of one mole of water when an acid is neutralized by the base.

9. How much amount of heat is released when a weak acid reacts with the strong base?
a) < -57.1 kJ/mole
b) > -57.1 kJ/mole
c) >-77.8 kJ/mole
d) <-77.8 kJ/mole

Explanation: Whenever a weak acid (or base) reacts with a strong base (or acid), the release of heat is less than -57.1 kJ/mole. It is because these acids or bases are not completely ionized in solution.

10. What is the heat of neutralization for the strong acid + strong base?
a) -13.7 kcal/mole
b) 13.7 kcal/mole
c) 22.4 kcal/mole
d) -22.4 kcal/mole

Explanation: For the strong acid + strong base, the heat of neutralization is always equal to -13.7 kcal/mole or -57.1 kJ/mole. For any other combination, this heat is less than -13.7 kcal/mole or -57.1 kJ/mole.

Sanfoundry Global Education & Learning Series – Physical Chemistry.

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