Chapter 13: Problem 24
What energy is required to raise the temperature of \(450 \mathrm{~g}\) of water by \(6^{\circ} \mathrm{C} ?\) (a) \(4200 \mathrm{~J}\); (b) \(5200 \mathrm{~kJ} ;\) (c) \(6600 \mathrm{~kJ}\); (d) \(11,300 \mathrm{~J}\).
Short Answer
Expert verified
The energy required is approx. \( 11,300 \text{ J} \) (option d).
Step by step solution
01
Understand the Formula
To calculate the energy required to raise the temperature, we use the formula \( Q = mc\Delta T \), where \( Q \) is the heat energy, \( m \) is the mass, \( c \) is the specific heat capacity, and \( \Delta T \) is the change in temperature. For water, the specific heat capacity \( c \) is \( 4.18 \text{ J/g°C} \).
02
Identify Given Values
From the problem, we know the mass \( m = 450 \text{ g} \) and the temperature change \( \Delta T = 6°C \).
03
Apply the Formula
Substitute the known values into the formula: \( Q = (450 \text{ g}) \times (4.18 \text{ J/g°C}) \times (6°C) \).
04
Calculate the Energy
Perform the multiplication to find \( Q \):\[Q = 450 \times 4.18 \times 6 = 11286 \text{ J}\]
05
Select the Best Option
Compare the calculated energy value with the options provided in the question. The closest option to \( 11286 \text{ J} \) is \( 11,300 \text{ J} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Specific Heat Capacity
Specific heat capacity is a fundamental property of materials that tells us how much energy is needed to change the temperature of a given mass of a substance by one degree Celsius. For instance, water has a specific heat capacity of approximately 4.18 J/g°C.
- This means you need 4.18 joules of energy to raise the temperature of 1 gram of water by 1°C.
- The higher the specific heat capacity, the more energy is required to change the temperature.
- Specific heat plays a crucial role in many real-world applications, such as climate modeling and cooking.
- It helps us understand why it takes longer to heat water compared to substances with lower specific heat capacities.
Temperature Change
Temperature change is a key factor when calculating the amount of heat energy needed in a process. It is simply the difference between the final and initial temperatures. In our exercise, the water's temperature is raised by 6°C.
- It is represented by the symbol \( \Delta T \), where \( \Delta \) indicates a change and \( T \) stands for temperature.
- A positive temperature change means an increase in temperature, while a negative change indicates cooling.
- Understanding temperature change is essential for many scientific and engineering applications, such as energy management and materials science.
Energy Formula
The energy formula \( Q = mc\Delta T \) is vital in physics for calculating how much energy is required to bring about a temperature change in a substance.
- Here, \( Q \) stands for the heat energy absorbed or released, measured in joules.
- \( m \) represents the mass of the substance, which is crucial as it scales the energy requirement proportionally.
- \( c \) is the specific heat capacity, a constant that varies with different substances.
- \( \Delta T \) represents the change in temperature, a crucial parameter in evaluating energy needs.
Physics Problem Solving
Solving physics problems, such as calculating heat energy, involves systematic approaches to ensure accuracy and comprehension.
- First, understand the problem and identify the known and unknown values.
- Apply relevant formulas, like \( Q = mc\Delta T \), replacing variables with the given values.
- Perform calculations carefully, double-checking each step.
- Compare your result with provided options or benchmark values for validation.
- Finally, reflect on the solution to ensure it aligns with physical intuition, such as whether the calculated energy seems reasonable given the circumstances.