Lesson 4.2 • Competency 4.3Complete Lesson
Back to UnitCalorimetry and Latent Heat
Specific heat capacity (Q = mcΔθ), latent heat of fusion (L_f) and vaporization (L_v), method of mixtures with radiation loss corrections, and Newton’s Law of Cooling.
Marking a lesson complete represents finishing your study of the topic; it does not denote tested mastery.
Learning Objectives
- Apply heat energy conservation to multi-phase mixtures involving melting ice and condensing steam.
- Explain experimental precautions in latent heat measurements (dry ice, steam trap, cooling compensation).
Core Theory & Concepts
Calorimetry quantifies the transfer of thermal energy during temperature changes and constant-temperature phase transformations, governed by the conservation of energy.
Conservation of Heat Energy in Mixtures
In an isolated calorimeter: Total Heat Lost by Hot Bodies = Total Heat Gained by Cold Bodies.
Σ Q_lost = Σ Q_gained
Latent Phase Transformation
During melting or boiling, temperature remains constant as absorbed energy breaks intermolecular bonds: Q = m · L.
Q = m · L
Common Misconceptions
Misconception
When water is boiling at 100 °C, continuing to supply heat makes the liquid water hotter than 100 °C.
Physical Clarification:At constant atmospheric pressure, liquid water cannot exceed 100 °C. All added heat supplies latent heat of vaporization (L_v) converting liquid into steam.
Syllabus Topic Outline
- 1Sensible heat transfer: Q = m · c · Δθ
- 2Latent heat of fusion of ice (L_f ≈ 3.34 × 10⁵ J/kg)
- 3Latent heat of vaporization of water (L_v ≈ 2.26 × 10⁶ J/kg)
- 4Newton’s Law of Cooling: dθ/dt = -k(θ - θ₀)