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
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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
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Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: From the data below, calculate the heat (kJ) involved in the transformation of 0.450 mol of ethanol (CH3CH2OH) gas at 275°C and 1 atm to solid ethanol at -116°C.

Problem

From the data below, calculate the heat (kJ) involved in the transformation of 0.450 mol of ethanol (CH3CH2OH) gas at 275°C and 1 atm to solid ethanol at -116°C.


Solution

We’re being asked to calculate the amount of energy released when 0.450 moles of ethanol gas is cooled from 275 ˚C to -116.0 ˚C (solid ethanol).


Note that cooling and freezing is an exothermic process, which means q is negative (–)


There are two heats involved in this problem:

1. q1 which is the heat in cooling 0.450 moles of gaseous ethanol from 275 ˚C to 78.5 ˚C

2. q2 which is the heat in condensing 0.450 moles of H2O at 78.5 ˚C

3. q3 which is the heat in cooling 0.450 moles of liquid ethanol from 78.5 ˚C to -114˚C

4. q3 which is the heat in freezing 0.450 moles of H2O at -114˚C

5. q3 which is the heat in cooling 0.450 moles of solid ethanol from -114˚C to -116 ˚C


We need to solve for each heat individually then add them together to get the final answer.


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