Free Evaporation, Boiling Point and Vapour Pressure MCQs with Answers
107 Evaporation, Boiling Point and Vapour Pressure MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Evaporation is the escape of higher-energy molecules from a liquid surface, while vapour pressure is the pressure exerted by vapour in equilibrium with that liquid. The topic distinguishes evaporation from boiling and relates both to temperature, intermolecular forces, surface area, atmospheric pressure and the boiling point.
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107 questions · page 2 of 6
- A. Molar heat of sublimation
- B. Molar heat of fusion
- C. Molar heat of vapourization
- D. Latent heat of that liquid
Explanation: The heat required to convert one mole of liquid into gas at its boiling point is the molar heat, or molar enthalpy, of vaporization.
Correct answer: Molar heat of vapourization- A. 40.7 KJ/mole
- B. 40.7 J/mole
- C. 40.7 cal/mole
- D. 40.7 Kcal/mole
Explanation: The molar heat of vaporization of water is the heat required to convert 1 mole of liquid water into vapour at its boiling point, and its…
Correct answer: 40.7 KJ/mole- A. Ion dipole forces
- B. London forces
- C. Hydrogen bonding
- D. Dipole dipole forces
Explanation: The boiling points of noble gases increase down Group 18 because larger atoms have more electrons and stronger London dispersion forces.
Correct answer: London forces- A. crystallization
- B. evaporization
- C. vaporization
- D. condensation
Explanation: Condensation is the change of a vapour into a liquid, usually when the vapour loses heat.
Correct answer: condensation- A. Latent heat of fusion
- B. Latent heat of vaporization
- C. Latent heat of sublimation
- D. All of the above
Explanation: Steam contains the latent heat of vaporization absorbed when liquid water changed into vapour, in addition to its sensible heat; releasing…
Correct answer: Latent heat of vaporization- A. Surface phenomenon
- B. Continuous
- C. Exothermic
- D. Cause cooling
Explanation: Evaporation is a surface phenomenon that occurs continuously below the boiling point and causes cooling because higher-energy molecules…
Correct answer: Exothermic- A. increase
- B. remains constant
- C. decrease
- D. there will be no boiling
Explanation: At the boiling point, the liquid vapour pressure equals the external pressure, and additional heat is used to overcome intermolecular…
Correct answer: remains constant- A. Diethyl ether
- B. Ethyl alcohol
- C. Water
- D. Ethylene glycol
Explanation: Diethyl ether has weaker intermolecular attractions and a lower boiling point than ethanol, water, and ethylene glycol, so it escapes into…
Correct answer: Diethyl ether- A. Surface area
- B. temperature
- C. intermolecular forces
- D. atmospheric pressure
Explanation: For a liquid at a fixed temperature, vapour pressure depends mainly on the escaping tendency of its molecules, which is affected by…
Correct answer: Surface area- A. vapourization
- B. evaporation
- C. condensation
- D. cracking
Explanation: Evaporation is the escape of molecules from the surface of a liquid into the vapour phase, and it can occur below the boiling point.
Correct answer: evaporation- A. vaporization
- B. evaporation
- C. crystallization
- D. sublimation
Explanation: The molar heat of vaporization is the heat needed to convert 1 mole of liquid into vapour at its boiling point without changing…
Correct answer: vaporization- A. 55 mm Hg
- B. 760 mm Hg
- C. 355 mm Hg
- D. 1489 mm Hg
Explanation: At 100°C, water boils at normal atmospheric pressure because its vapour pressure equals 1 atmosphere, which is 760 mm Hg.
Correct answer: 760 mm Hg- A. Between 760 torr and 1200 torr
- B. Between 200 torr and 760 torr
- C. 765 torr
- D. any value of pressure
Explanation: Water boils when its vapour pressure equals the external pressure. Since water's vapour pressure at 110°C is greater than 760 torr and is…
Correct answer: Between 760 torr and 1200 torr- A. 8
- B. 5.1
- C. 6
- D. one/fifty one
Explanation: For a dilute solution of a non-volatile solute, relative lowering of vapour pressure equals the solute mole fraction.
Correct answer: one/fifty one- A. 40%
- B. 50%
- C. 60%
- D. 70%
Explanation: Relative humidity is the ratio of the partial pressure of water vapor present in the air to the vapor pressure of water at a particular…
Correct answer: 60%- A. Continuous
- B. Endothermic
- C. Exothermic
- D. Spontaneous
Explanation: The molecules are absorbing heat, evaporation is called endothermic. Remember, endo means "to enter" while thermic means "heat." So…
Correct answer: Exothermic- A. Temperature
- B. Intermolecular forces
- C. Density of liquid
- D. Surface area of liquid
Explanation: The surface area of liquid or solid in contact does not affect vapor pressure. Other factors do have an impact on vapor pressure.
Correct answer: Surface area of liquid- A. 120 oC
- B. 110 oC
- C. 100 oC
- D. 90 oC
Explanation: At a pressure of 1489 mmHg (millimeters of mercury), water will boil at approximately 120 degrees Celsius (212 degrees Fahrenheit).
Correct answer: 120 oC- A. Mercury pressure
- B. Glass pressure
- C. Atmospheric pressure
- D. Container pressure
Explanation: Option A) Mercury pressure and Option B) Glass pressure are incorrect because they do not have any direct relation to the measurement of…
Correct answer: Atmospheric pressure- A. Chloroform
- B. Methanol
- C. Water
- D. Ethanol
Explanation: The stronger the intermolecular forces, the lower the vapor pressure. Water has the strongest forces amongst these options (4 H-bonds)…
Correct answer: Water