This set of Physical Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Heat Capacities”.
1. Heat transfer to a system where there are no changes causes the temperature to change.
a) True
b) False
View Answer
Explanation: Heat transfer to a system in which there are no phase transitions, no chemical reactions, and no changes in composition causes the temperature of the system to change.
2. What is specific internal energy?
a) Internal energy per unit mass
b) Energy that comes from heat
c) The degree to which material conducts electricity
d) Power required for the utilization of physical sources
View Answer
Explanation: The molar or specific internal energy of a substance can be expressed as a function of two other state variables. It is defined as the internal energy per unit mass.
3. Ideal gas heat capacities increase with increasing temperature.
a) False
b) True
View Answer
Explanation: Ideal-gas heat capacities increase smoothly with increasing temperature toward an upper limit, which is reached when all translational, rotational, and vibrational modes of molecular motion are fully excited.
4. How two ideal gas capacities are related to each other?
a) CPig / R
b) CP / R
c) CP = A + BT + CT2 + DT-2
d) (CVig / R) = (CPig / R) – 1
View Answer
Explanation: The two ideal gas capacities are related as: (CVig / R) = (CPig / R) – 1. The temperature dependence of CVig / R follows from the temperature dependence of CPig / R.
5. Which statement is correct for latent heat of fusion?
a) No temperature changes when substance is liquefied from solid state
b) It is a form of potential energy which can be absorbed or released during chemical reaction
c) Change of free energy that accompanies the formation of 1 mole
d) It is the measure of bond strength in the chemical bond
View Answer
Explanation: When a pure substance is liquefied from the solid state or vaporized state from the liquid at constant pressure, no change in temperature occurs.
6. What is Trouton’s rule?
a) ΔH = T
b) (ΔHn / R Tn) ≈ 10
c) ΔHn ≈ 5
d) ΔH = T Δ V
View Answer
Explanation: Rough estimates of latent heat of vaporization for pure liquids at their normal boiling points are given by Trouton’s rule: (ΔHn / R Tn) ≈ 10, where Tn is the absolute temperature of the normal boiling point.
7. What is the standard heat of reaction?
a) It is a particular state of species at specified conditions
b) Infinite delusion in a specific solution
c) When two phases are in equilibrium, the state of the system is fixed
d) When a system is in contact with an outside thermal reservoir, the change will occur slowly
View Answer
Explanation: A standard state is a particular state of species at temperature T and at specified conditions of pressure, composition, and physical condition as, e.g., gas, liquid, or solid.
8. What is the standard heat of formation?
a) Energy that comes from heat
b) It determines whether the reaction is spontaneous or not
c) A reaction which forms a single compound from its constituent elements
d) Energy required to convert solid to liquid state
View Answer
Explanation: It is the change of enthalpy during the formation of the 1 mole of the substance from its constituent element.
9. What is the standard heat of combustion?
a) A reaction between elements or compounds and oxygen to form specified combustion products
b) It is a process of burning something
c) A process which entails only partial burning of fuel
d) Rapid combination of oxygen with substance
View Answer
Explanation: A combustion of reaction is defined as the reaction between an element or compound and oxygen to form specified combustion products. For organic compounds made up of carbon, hydrogen, and oxygen only, the products are carbon dioxide and water, but the state of the water may be either vapor or liquid. Data are always based on 1 mole of the substance burned.
10. What is the SI unit of heat capacity?
a) Joule/Kelvin
b) Joule
c) Joule/kilogram
d) Joule / (kilogram × Kelvin)
View Answer
Explanation: Heat capacity is defined as the amount of heat needed to raise the system’s temperature by one degree. Its SI unit is Joule/Kelvin.
Sanfoundry Global Education & Learning Series – Physical Chemistry.
To practice all areas of Physical Chemistry, here is complete set of Multiple Choice Questions and Answers.
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