Food Processing Unit Operations Multiple Choice Questions on “Solid Liquid Equilibrium”.
1. At what point does liquid and solid exist at equilibrium?
a) Double point
b) Triple point
c) Dew point
d) Freezing point
Answer: b
Clarification: The point at which the lines of liquid, solid and gas intersect represents the triple point. At the pressure and temperature of the triple point, all the phases exist in equilibrium.
2. Is the value of equilibrium constant independent of initial concentrations of the reactants and products?
a) True
b) False
Answer: a
Clarification: The value of equilibrium constant is independent of initial concentrations of the reactants and products. It is applicable only when concentrations of the reactants and products have attained their equilibrium state and is temperature dependent.
3. Who coined the term triple point?
a) James Thomson
b) Daniel Gabriel Fahrenheit
c) Carrier
d) Rudolf Clausius
Answer: a
Clarification: James Thomson coined the term triple point. Daniel Gabriel Fahrenheit invented thermometer. Carrier discovered that law of constant dew-point depression. Rudolf Clausius coined the term entropy.
4. Which of the following is not an example of freezing point depression?
a) Salt in water
b) Cooling the hot water
c) Alcohol in water
d) Mixing of impurities into a fine powder
Answer: c
Clarification: The freezing point depression is the decrease of the freezing point of a solvent on the addition of a non-volatile solute. Examples like alcohol in water, salt in water and the mixing of two solids such as impurities into a finely powdered drug.
5. What is peritectic?
a) A reaction between solid phase and gas phase to form a second solid phase
b) A reaction between solid phase and liquid phase to form a second solid phase
c) A reaction between gas phase and liquid phase to form a second solid phase
d) A reaction between solid phase and liquid phase to form a second liquid phase
Answer: b
Clarification: A reaction between solid phase and liquid phase to form a second solid phase is called peritectic reaction. These reactions are slow as the product phase form at the boundary between the two reacting phases thus it separates them and slows down the further reaction.
6. Are these statements about the dynamic equilibrium true?
Statement 1: Opposing processes occur at the same time.
Statement 2: Two processes occur at the same rate.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: When the system of ice and water is in dynamic equilibrium it can be concluded that both opposing processes occur at the same time and two processes occur at the same rate therefore the amount of ice and water remain constant.
7. What is the temperature at which the solid and liquid phases are at equilibrium?
a) Normal melting point
b) Bubble point
c) Dew point
d) Equilibrium point
Answer: a
Clarification: For any pure substance at atmospheric pressure, the temperature at which the solid and liquid phases are at equilibrium is called the normal freezing point or normal melting point of the component.
8. At equilibrium, the concentrations of N2=4.0 x10-3M, O2 = 5.2 x 10-3M and NO=3.9×10-3M in a sealed vessel at 800K. What will be Kc for the reaction?
a) 0.731
b) 0.073
c) 7.31
d) 0.0007
Answer: a
Clarification: For the reaction equilibrium constant, Kc can be written as,
Kc = [NO]2/[N2][O2]
= (3.9 x 10-3)2/(4.0×10-3M)(5.2×10-3M)
= 0.731
9. Is rate law and law of mass action are same?
a) True
b) False
Answer: b
Clarification: The difference between rate law and law of mass action is that, rate law considers only the reactants of a reaction whereas law of mass action considers both reactants and products of a reaction.
10. What is the other alternative name for equilibrium phase diagram?
a) p-v-T diagram
b) Bubble point diagram
c) Dew point diagram
d) Equilibrium point diagram
Answer: a
Clarification: The p-v-T diagram is also called as equilibrium phase diagram. The equilibrium conditions are explained with areas for solid, liquid, and vapor phases. It shows the areas where solid and liquid, solid and vapor, or liquid and vapor coexist in equilibrium.