Dynamic equilibrium, equilibria involving physical processes, Henry's law - Question Bank

1. Dynamic equilibrium is characterized by:
A) Constant concentrations of reactants and products.
B) Equal concentrations of reactants and products.
C) Constant rates of forward and reverse processes.
D) A net zero rate for both forward and reverse processes.
2. Which of the following physical processes is LEAST likely to be described by Henry's Law?
A) Dissolving oxygen in water.
B) Dissolving nitrogen in water.
C) Dissolving ammonia in water.
D) Dissolving carbon dioxide in water.
3. The temperature at which the vapor pressure of a liquid is equal to the external pressure is called the:
A) Melting point
B) Freezing point
C) Boiling point
D) Critical temperature
4. A system is at equilibrium when:
A) The forward reaction rate is zero.
B) The reverse reaction rate is zero.
C) The forward and reverse reaction rates are equal.
D) The system is no longer changing macroscopically or microscopically.
5. If the Henry's law constant for a gas is 1.25 x 10^5 atm at a certain temperature, and the mole fraction of the gas in the liquid is 0.01, what is the partial pressure of the gas?
A) 1250 atm
B) 12500 atm
C) 0.01 atm
D) 1.25 atm
6. The equilibrium between solid iodine and iodine vapor is an example of:
A) Phase equilibrium
B) Chemical equilibrium
C) Solution equilibrium
D) Gas-phase equilibrium
7. According to Henry's Law, the solubility of gases like O2 and N2 in blood at sea level is sufficient for respiration. However, during deep dives, the increased partial pressure leads to:
A) Reduced solubility of these gases.
B) Increased solubility of these gases.
C) No change in solubility.
D) Formation of nitrogen trioxide.
8. Which of the following conditions is necessary for dynamic equilibrium?
A) The system must be open.
B) The temperature must be constant.
C) The system must be closed.
D) The pressure must be constant.
9. The equilibrium between liquid water and steam at 100°C and 1 atm is an example of:
A) Chemical equilibrium
B) Phase equilibrium
C) Solute-solvent equilibrium
D) Gas-phase equilibrium
10. When a gas is dissolved in a liquid, the process is generally:
A) Endothermic and leads to an increase in entropy.
B) Exothermic and leads to a decrease in entropy.
C) Exothermic and leads to an increase in entropy.
D) Endothermic and leads to a decrease in entropy.
11. The constant KH in Henry's law has units of:
A) Pressure
B) Mole fraction
C) Pressure per mole fraction (e.g., atm/mole fraction)
D) Inverse mole fraction
12. Henry's Law is an empirical law that describes the behavior of:
A) Solid-gas equilibria.
B) Liquid-liquid equilibria.
C) Gas-liquid equilibria.
D) Solid-liquid equilibria.
13. The equilibrium between a solution and undissolved solid is characterized by:
A) The rate of dissolution being greater than the rate of precipitation.
B) The rate of precipitation being greater than the rate of dissolution.
C) The rate of dissolution being equal to the rate of precipitation.
D) The solution being unsaturated.
14. Which of the following is a characteristic of a system at equilibrium?
A) It is a static state.
B) It is dynamic.
C) It can be easily disturbed.
D) It requires continuous addition of energy.
15. According to Henry's Law, the solubility of a gas in a liquid is proportional to the partial pressure of the gas above the liquid. If the partial pressure is doubled, the solubility will:
A) Halve
B) Double
C) Remain the same
D) Become zero
16. A system is at equilibrium when:
A) The rates of forward and reverse processes are zero.
B) The rates of forward and reverse processes are equal and non-zero.
C) The concentrations of reactants and products are equal.
D) The system is open to exchange matter and energy.
17. The equilibrium constant for the physical process of sublimation (Solid <=> Gas) is directly related to:
A) The partial pressure of the gas.
B) The vapor pressure of the solid.
C) The concentration of the solid.
D) The rate of sublimation.
18. Which of the following is a consequence of Henry's Law in biological systems?
A) Oxygen transport in the blood.
B) Carbon dioxide transport in the blood.
C) Nitrogen narcosis at high pressure.
D) All of the above
19. When a liquid is heated to its boiling point at a given pressure, the equilibrium established is between:
A) Liquid and solid phases
B) Liquid and gas phases
C) Solid and gas phases
D) Dissolved solute and solid solute
20. If KH for a gas is very high, it means the gas is:
A) Highly soluble in the solvent.
B) Sparingly soluble in the solvent.
C) Insoluble in the solvent.
D) A perfect gas
21. The equilibrium between a solid and its vapor is characterized by:
A) Constant vapor pressure at a given temperature.
B) Varying vapor pressure with temperature.
C) Zero vapor pressure.
D) Vapor pressure dependent on the amount of solid.
22. Which of the following statements about dynamic equilibrium is incorrect?
A) It can only be achieved in a closed system.
B) It is a state of balance between opposing processes.
C) It implies that the net change in observable properties is zero.
D) It means that the reaction has reached completion.
23. At equilibrium, the rate of sublimation of a solid is equal to the rate of:
A) Melting
B) Deposition
C) Condensation
D) Fusion
24. Henry's Law is applicable to:
A) Ideal solutions only
B) Dilute solutions only
C) Concentrated solutions only
D) All types of solutions
25. Which of the following is an example of equilibrium involving physical processes?
A) Dissociation of PCl5
B) Formation of ammonia
C) Dissolving of sugar in water to form a saturated solution
D) Combustion of methane
26. The solubility of gases in liquids generally decreases with an increase in temperature because:
A) The dissolution process is usually exothermic.
B) The dissolution process is usually endothermic.
C) The gas molecules gain kinetic energy and escape the liquid.
D) The liquid molecules gain kinetic energy and dissolve more gas.
27. Which factor does NOT affect the position of physical equilibrium for a solid-liquid phase transition at constant pressure?
A) Temperature
B) Pressure
C) Presence of an inert gas
D) Nature of the solid and liquid
28. According to Henry's Law, if the mole fraction of a gas in a solution increases, its partial pressure above the solution will:
A) Decrease
B) Increase
C) Remain the same
D) Become zero
29. Consider the equilibrium: H2O(l) <=> H2O(g). The vapor pressure of water at a given temperature is:
A) The partial pressure of H2O(g) at equilibrium.
B) The total pressure of the system.
C) The concentration of H2O(l).
D) The rate of evaporation.
30. The equilibrium constant for a physical equilibrium involving phase change is typically related to:
A) Concentrations of reactants and products.
B) Partial pressures of gases.
C) Vapor pressures of liquids or solids.
D) Activities of species involved.
31. Which statement is NOT true for a system at dynamic equilibrium?
A) The net rate of reaction is zero.
B) The forward and reverse reaction rates are equal.
C) Macroscopic properties are constant.
D) The reaction has stopped.
32. The equilibrium established between solid solute and its saturated solution is called:
A) Solubility equilibrium
B) Solution equilibrium
C) Solid-solution equilibrium
D) All of the above
33. In a saturated solution in contact with excess solute, the process of dissolution and crystallization are in equilibrium. This is a type of:
A) Chemical equilibrium
B) Physical equilibrium
C) Phase equilibrium
D) Gas-liquid equilibrium
34. Which physical process reaches dynamic equilibrium when the rate of evaporation equals the rate of condensation?
A) Melting of ice
B) Boiling of water
C) Sublimation of dry ice
D) Evaporation of a liquid in a closed container
35. Carbonated beverages are bottled under high pressure of carbon dioxide. When the bottle is opened, the pressure decreases, and CO2 comes out of solution. This illustrates:
A) Le Chatelier's Principle
B) Henry's Law
C) The concept of dynamic equilibrium
D) The solubility product principle
36. When a diver ascends from a deep sea dive, the rapid decrease in external pressure causes dissolved gases in the blood to form bubbles. This is a consequence of:
A) Decreased solubility of gases at lower pressure (Henry's Law).
B) Increased solubility of gases at lower pressure (Henry's Law).
C) The partial pressure of gases decreasing significantly.
D) The formation of a new chemical compound.
37. The phenomenon of 'the bends' or decompression sickness is related to the application of which law?
A) Dalton's Law of Partial Pressures
B) Raoult's Law
C) Henry's Law
D) Gay-Lussac's Law
38. Which of the following gases is least soluble in water at room temperature and pressure, according to Henry's Law trends?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Ammonia
39. For most gases, the value of KH increases with increasing temperature. This implies that the solubility of these gases in liquids:
A) Increases with increasing temperature.
B) Decreases with increasing temperature.
C) Remains unaffected by temperature.
D) Becomes zero at high temperatures.
40. The Henry's law constant (KH) is dependent on:
A) The amount of gas present.
B) The volume of the liquid.
C) The nature of the gas and the solvent, and temperature.
D) The pressure of the gas only.
41. Mathematically, Henry's Law is expressed as P = KH * X, where P is the partial pressure of the gas, KH is the Henry's law constant, and X is:
A) The mole fraction of the solvent.
B) The mole fraction of the gas in the liquid.
C) The total mole fraction of all gases.
D) The solubility of the gas in moles per liter.
42. Henry's Law states that the partial pressure of a gas in equilibrium with a liquid is:
A) Inversely proportional to its mole fraction in the liquid.
B) Directly proportional to its mole fraction in the liquid.
C) Independent of its mole fraction in the liquid.
D) Equal to the total pressure of the liquid.
43. The equilibrium between a liquid and its vapor at a constant temperature is known as:
A) Solvent equilibrium
B) Vapor pressure equilibrium
C) Phase equilibrium
D) Gas-liquid equilibrium
44. When ice melts at 0°C and 1 atm pressure, the system is in:
A) Chemical equilibrium
B) Dynamic equilibrium between solid and liquid phases
C) A state of no net change
D) A state where the reverse reaction is dominant
45. Which of the following is an example of physical equilibrium?
A) N2(g) + 3H2(g) <=> 2NH3(g)
B) H2O(l) <=> H2O(g)
C) CH3COOH(aq) + C2H5OH(aq) <=> CH3COOC2H5(aq) + H2O(l)
D) CaCO3(s) <=> CaO(s) + CO2(g)
46. The equilibrium that involves changes in physical states, such as melting or boiling, is called:
A) Chemical equilibrium
B) Homogeneous equilibrium
C) Physical equilibrium
D) Heterogeneous equilibrium
47. Consider the reversible reaction A + B <=> C + D. If the system is at equilibrium, which statement is correct?
A) [A] = [B] and [C] = [D]
B) Rate of forward reaction > Rate of reverse reaction
C) Rate of forward reaction < Rate of reverse reaction
D) Rate of forward reaction = Rate of reverse reaction
48. In a system at dynamic equilibrium, what is true about the macroscopic properties?
A) They change continuously.
B) They remain constant.
C) They fluctuate randomly.
D) They are immeasurable.
49. Which of the following best describes dynamic equilibrium in a reversible reaction?
A) The reaction has stopped, and no more products or reactants are present.
B) The rate of the forward reaction is equal to the rate of the reverse reaction.
C) The concentration of reactants and products remains constant but not necessarily equal.
D) The reaction proceeds only in the forward direction until all reactants are consumed.
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