Textbook Question
Identify each of the following changes of state as melting, freezing, sublimation, or deposition:
c. Heat is removed from 125 g of liquid water at 0 °C.
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Ch.3 Matter and Energy
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353
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Table of contents
- Ch.1 Chemistry in Our Lives11
- Ch.2 Chemistry and Measurements80
- Ch.3 Matter and Energy54
- Ch.4 Atoms and Elements51
- Ch.5 Nuclear Chemistry42
- Ch.6 Ionic and Molecular Compounds57
- Ch.7 Chemical Quantities and Reactions41
- Ch.8 Gases29
- Ch.9 Solutions51
- Ch.10 Acids and Bases and Equilibrium65
- Ch.11 Introduction to Organic Chemistry: Hydrocarbons78
- Ch.12 Alcohols, Thiols, Ethers, Aldehydes, and Ketones83
- Ch.13 Carbohydrates54
- Ch.14 Carboxylic Acids, Esters, Amines, and Amides90
- Ch.15 Lipids61
- Ch.16 Amino Acids, Proteins, and Enzymes84
- Ch.17 Nucleic Acids and Protein Synthesis83
- Ch.18 Metabolic Pathways and ATP Production67
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 3, Problem 41c
Use the heat equation to calculate the energy, in joules and calories, for each of the following (see TABLE 3.11):
c. lost when 15.0 g of ethanol, C2H6O, cools from 60.5 °C to −42.0 °C
Verified step by step guidance1
Step 1: Identify the heat equation to use: \( q = m \cdot c \cdot \Delta T \), where \( q \) is the heat energy, \( m \) is the mass, \( c \) is the specific heat capacity, and \( \Delta T \) is the change in temperature.
Step 2: Determine the values given in the problem: \( m = 15.0 \; \text{g} \), \( \Delta T = T_{\text{final}} - T_{\text{initial}} = -42.0 \; ^\circ\text{C} - 60.5 \; ^\circ\text{C} \), and the specific heat capacity of ethanol (not methanol) must be obtained from a reliable source, as the table provided does not include ethanol.
Step 3: Calculate \( \Delta T \): Subtract the final temperature from the initial temperature to find the temperature change. Ensure the sign is correct, as cooling results in a negative \( \Delta T \).
Step 4: Substitute the values into the heat equation for both joules and calories. Use the specific heat capacity in \( \text{J/g} \cdot ^\circ\text{C} \) for joules and \( \text{cal/g} \cdot ^\circ\text{C} \) for calories.
Step 5: Perform the calculations separately for joules and calories to find the energy lost. Ensure unit consistency throughout the calculation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heat Equation
The heat equation is a formula used to calculate the amount of heat energy absorbed or released by a substance when its temperature changes. It is expressed as Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. This equation is fundamental in thermodynamics and helps in understanding energy transfer in physical processes.
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Heat Capacity
Specific Heat Capacity
Specific heat capacity is a property of a substance that indicates the amount of heat required to change the temperature of one gram of the substance by one degree Celsius. It varies between different materials and is crucial for calculating heat transfer. In this case, the specific heat capacity of ethanol will be needed to determine the energy lost as it cools from 60.5 °C to −42.0 °C.
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Energy Conversion (Joules to Calories)
Energy conversion between joules and calories is important in thermodynamics, as these units measure energy in different contexts. One calorie is equivalent to approximately 4.184 joules. When calculating energy changes, it may be necessary to convert between these units to provide results in the desired format, such as joules for scientific contexts or calories for nutritional contexts.
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Related Practice
Textbook Question
If the same amount of heat is supplied to samples of 10.0 g each of aluminum, iron, and copper all at 15.0 °C, which sample would reach the highest temperature (see TABLE 3.11)?
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Textbook Question
Identify each of the following changes of state as melting, freezing, sublimation, or deposition:
a. Dry ice in an ice-cream cart disappears.
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Textbook Question
For dinner, Charles had one cup of clam chowder, which contains 16 g of carbohydrate, 12 g of fat, and 9 g of protein. How much energy, in kilocalories and kilojoules, is in the clam chowder? (Round off the answer for each food type to the tens place.)
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Textbook Question
A patient receives 3.2 L of intravenous (IV) glucose solution. If 100. mL of the solution contains 5.0 g of glucose (carbohydrate), how many kilocalories did the patient obtain from the glucose solution?
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Textbook Question
Identify each of the following changes of state as melting, freezing, sublimation, or deposition:
b. Snow on the ground turns to liquid water.
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