Questions about the Heat of Solution
Multiple-Choice Questions: Heat of Solution
1. What does the term “heat of solution” refer to?
A) Heat required to boil a solvent
B) Heat released when a solid condenses
C) Heat absorbed or released when a solute dissolves in a solvent
D) Heat needed to change a gas into a liquid
E) Heat used to raise the temperature of a solute
2. If the dissolution of a salt causes the temperature of the solution to increase, the process is:
A) Isothermal
B) Endothermic
C) Exothermic
D) Neutral
E) Sublimation
3. In an endothermic dissolution, the heat of solution is:
A) Negative
B) Positive
C) Zero
D) Infinite
E) Neutral
4. What sign (positive or negative) does the heat of solution have in an exothermic process?
A) Positive
B) Negative
C) Zero
D) Undefined
E) Alternating
5. Which of the following substances dissolves in water with a release of heat?
A) Potassium chloride (KCl)
B) Barium hydroxide (Ba(OH)₂)
C) Ammonium nitrate (NH₄NO₃)
D) Sodium chloride (NaCl)
E) Glucose (C₆H₁₂O₆)
6. Which process does not occur during dissolution?
A) Breaking solute-solute interactions
B) Formation of solute-solvent interactions
C) Boiling the solution
D) Breaking solvent-solvent interactions
E) Energy exchange
7. What is the unit commonly used for heat of solution?
A) g/mol
B) J/mol
C) atm·L
D) K
E) M/s
8. The total heat of solution depends on:
A) The solute only
B) The solvent only
C) Both solute and solvent interactions
D) Volume of gas
E) Vapor pressure
9. When ammonium nitrate dissolves in water, the container feels cold. This indicates:
A) A radioactive process
B) An exothermic reaction
C) An endothermic reaction
D) No heat exchange
E) Evaporation
10. Which interaction releases energy during solution formation?
A) Solute-solute
B) Solvent-solvent
C) Solute-solvent
D) All of the above
E) None of the above
11. The heat of solution can be calculated using:
A) Q = mcΔT
B) PV = nRT
C) M₁V₁ = M₂V₂
D) ΔG = ΔH – TΔS
E) Q = nCvΔT
12. A positive heat of solution indicates that:
A) Heat is released
B) Solution is radioactive
C) Process is endothermic
D) No bonds are broken
E) Pressure increases
13. If a solute has a large positive heat of solution, what might happen?
A) It will evaporate quickly
B) Its dissolution may lower the temperature of the solution
C) It will explode
D) It will decrease the vapor pressure
E) It will boil easily
14. What happens to the surroundings during an exothermic dissolution?
A) They cool down
B) They stay the same
C) They absorb heat
D) They heat up
E) Nothing happens
15. Which of the following is most likely to have a negative heat of solution?
A) Sodium hydroxide (NaOH)
B) Ammonium nitrate (NH₄NO₃)
C) Urea
D) Ethanol
E) Sugar
16. Which of the following steps is always endothermic during the solution process?
A) Formation of ion-dipole interactions
B) Solute-solute attraction
C) Solvent-solvent interaction
D) Separation of solute particles
E) Heat release
17. The heat of solution is often used to describe:
A) The density of a solute
B) The pressure of gases
C) Energy change during dissolution
D) The rate of solubility
E) The viscosity of liquids
18. Which term best describes the overall change in energy when a solute dissolves in a solvent?
A) Enthalpy of dissolution
B) Activation energy
C) Heat capacity
D) Bond energy
E) Lattice energy
19. The heat of solution is important in determining:
A) Color of the solution
B) Final volume
C) Whether dissolution is spontaneous
D) Solubility and thermal behavior
E) The freezing point
20. What is a likely consequence of a highly exothermic dissolution?
A) Container becomes cold
B) No observable temperature change
C) Container becomes warm or hot
D) Evaporation occurs
E) Crystals form immediately
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Answers and Explanations
1. C – The heat of solution refers to the heat absorbed or released when a solute dissolves in a solvent.
2. C – If the temperature increases, heat is being released, indicating an exothermic process.
3. B – Endothermic processes absorb heat, so their enthalpy (ΔH) is positive.
4. B – Exothermic processes release heat, and the heat of solution is negative.
5. B – Barium hydroxide dissolves exothermically, releasing heat.
6. C – Boiling does not occur during the normal dissolution process.
7. B – Heat of solution is measured in joules per mole (J/mol).
8. C – It depends on the interactions between both the solute and solvent.
9. C – If the container feels cold, it’s because heat is absorbed from the surroundings — endothermic.
10. C – Solute-solvent interactions release energy.
11. A – Q = mcΔT is used to calculate the heat exchange.
12. C – A positive heat of solution means the process absorbs energy — endothermic.
13. B – A large positive heat of solution can cause the solution’s temperature to drop.
14. D – In exothermic dissolution, surroundings heat up due to energy release.
15. A – Sodium hydroxide dissolves with a large release of energy — negative heat of solution.
16. D – Separating solute particles always requires energy — it’s endothermic.
17. C – Heat of solution represents the energy change during the dissolution.
18. A – The term “enthalpy of dissolution” is another name for the heat of solution.
19. D – Heat of solution impacts solubility and thermal behavior (e.g., cooling or warming).
20. C – In highly exothermic dissolutions, the solution releases a lot of heat, warming the container.
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