Understanding and calculating specific heat is a fundamental concept in physics and chemistry, providing insights into how much heat energy is needed to change the temperature of a substance. This worksheet delves into the principles of specific heat, offering a comprehensive guide to solving related problems with an answer key for instant help.
Key Concepts
Before tackling specific heat problems, let’s revisit some essential concepts:
- Specific Heat Capacity: The amount of heat per unit mass required to raise the temperature by one degree Celsius. Its unit is usually J/kg°C or kJ/kg°C.
- Heat Transfer Equation: Q = mcΔT, where Q is the heat added or removed, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.
- Unit Conversion: Being adept at converting between different units (like calories to joules) is crucial.
Solving Specific Heat Problems
Here are step-by-step instructions to solve problems related to specific heat:
Step 1: Identify the Variables
- Identify the mass (m) of the substance.
- Determine the specific heat capacity © if it’s not given.
- Find the initial and final temperatures (T₁ and T₂) to calculate ΔT.
Step 2: Apply the Heat Transfer Equation
Use the formula Q = mcΔT to calculate the heat energy transferred.
Example Calculation
Let’s work through an example where you need to find the heat energy required to raise the temperature of 10 kg of water from 20°C to 50°C. The specific heat capacity of water is 4.18 J/g°C.
| Variable | Value | Units |
|---|---|---|
| Mass (m) | 10 kg | - |
| Specific Heat Capacity (c) | 4.18 J/g°C | - |
| ΔT | 50°C - 20°C = 30°C | - |
| Heat Transfer (Q) | mcΔT = (10,000 g) * (4.18 J/g°C) * 30°C | J |
| Calculated Heat Transfer (Q) | 1,254,000 J | - |
💡 Note: Convert the mass of water from kg to g (1 kg = 1000 g) since the specific heat capacity is given in J/g°C.
Common Pitfalls
When solving specific heat problems, be aware of the following:
- Using the correct units for specific heat capacity.
- Paying attention to temperature change (ΔT) rather than just final or initial temperature.
- Accounting for heat lost or gained from the environment.
Worksheet Answers
Here’s an answer key for the common specific heat problems:
Question 1:
Calculate the heat energy required to heat 50 g of copper from 25°C to 75°C. Specific heat of copper is 0.385 J/g°C.
Q = mcΔT = 50 g * 0.385 J/g°C * 50°C = 962.5 J
Question 2:
How much heat must be absorbed by 200 g of water to raise its temperature from 10°C to 60°C?
Q = mcΔT = 200 g * 4.18 J/g°C * 50°C = 41,800 J
Question 3:
Find the specific heat capacity of an unknown metal that absorbs 500 J of heat when 50 g of it is heated from 15°C to 35°C.
c = Q/(mΔT) = 500 J / (50 g * 20°C) = 0.5 J/g°C
In summary, the mastery of calculating specific heat involves understanding the principles of heat transfer, correctly applying the equation Q = mcΔT, and being cautious with units and conversions. The examples and answers provided here should help you grasp these concepts better. If you encounter difficulties, revisit the basic concepts and approach each problem with these steps in mind. This comprehensive guide to specific heat will not only assist you in solving current problems but also lay a solid foundation for future learning in thermodynamics.
What is specific heat capacity?
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Specific heat capacity is the amount of heat per unit mass required to raise the temperature of a substance by one degree Celsius. It is a measure of how much thermal energy a material can absorb without undergoing a phase change.
Why is specific heat capacity important?
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Understanding specific heat capacity allows us to predict how substances will respond to changes in temperature, which is crucial in fields like engineering, material science, and climate studies. It helps in designing systems for heating, cooling, or insulation.
How do I convert between different units of heat?
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To convert from calories to joules, multiply by 4.184 (since 1 calorie = 4.184 joules). For other units, you might need to use dimensional analysis or conversion factors provided in your textbook or reference materials.
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