Ch.11 - Liquids, Solids & Intermolecular ForcesWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Problem

Which of the following statements is(are) true?

(a) The enthalpy of vaporization is usually larger than the enthalpy of fusion because it takes less energy per mole to separate particles to form a gas than it takes to melt the same substance.

(b) When a substance undergoes a phase change, the temperature remains constant and the added energy is simply lost to the surroundings.

(c) As energy is added to a substance at the melting point, the substance is in equilibrium between its solid and liquid phases.

(d) Statements (a), (b), and (c) are all false.

(e) Only statements (b) and (c) are true.

Solution

We are asked which of the following statements is(are) true regarding phase change. 


Analyze each statement: 

(a) The enthalpy of vaporization is usually larger than the enthalpy of fusion because it takes less energy per mole to separate particles to form a gas than it takes to melt the same substance.

  • This statement is FALSE since if we look at a table of standard values, enthalpy of vaporization and fusion, enthalpy of vaporization is almost always higher. 


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