Ch.11 - Liquids, Solids & Intermolecular ForcesWorksheetSee all chapters
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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

Solution: Assume that the values given here for 1 mole of methanol are constant over the relevant temperature ranges.Melting Point176 KBoiling Point338 KHfus2.2 kJ/mol KHvap35.2 kJ/mol KCs,solid105 J/mol KCs,li

Solution: Assume that the values given here for 1 mole of methanol are constant over the relevant temperature ranges.Melting Point176 KBoiling Point338 KHfus2.2 kJ/mol KHvap35.2 kJ/mol KCs,solid105 J/mol KCs,li

Problem
Assume that the values given here for 1 mole of methanol are constant over the relevant temperature ranges.


Melting Point


176 K


Boiling Point


338 K


Hfus


2.2 kJ/mol K


Hvap


35.2 kJ/mol K


Cs,solid


105 J/mol K



Cs,liquid



81.3 J/mol K



Cs,gas


48 J/mol K


Given the heating curve for 1 mole of methanol beginning at 170 K and ending at 350 K answer the following questions:

A graph of heat added, in kilojoules per mole, versus temperature, in kelvins. The graph is composed of five line segments. The first represents heating the solid, it starts at (0,170), and ends at (.6,176). Segment two represents the solid melting, and starts at (.6,176), and ends at (2.8,176). Segment three represents the liquid being heated, it starts at (2.8, 176), and ends at (16, 338). Segment four represents the liquid being vaporized, it starts at (16,338), and ends at (51.2,338). Segment five represents the vapor heating, it starts at (51.2,338), and ends at (51.8,350).


What is the value of qsolid for methanol?

Solution

Given the heating curve for 1 mole of methanol, we are asked to calculate qsolid for methanol.

Recall: In Heating curves, we have the representation of the amount of heat absorbed during phase changes. As the reaction progress, a phase change or temperature change can occur.

During a phase change,

  • Temperature is constant
  • Avg. Kinetic Energy is constant
  • Heat is transferred into potential energy

During a temperature change.

  • Heat energy is converted into Kinetic Energy
  • Increase in temperature causes increase in Kinetic Energy
  • Decrease in temperature causes decrease in Kinetic Energy


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