Q = m c ΔTQ: J; m: kg; c: J·kg⁻¹·K⁻¹ ; ΔT: K or difference in °C.
Use when: Heating in a single phase with approximately constant c.
Changes of state
Distinguish between heating, phase change and ionization.
What is happening?
Energy supplied can increase the temperature of a phase or modify the proportion of two phases in equilibrium. For a pure body at fixed pressure, a phase change can take place at practically constant temperature.
Solid, liquid and gas differ in their organization and mobility. The plasma contains a fraction of charged particles; its appearance does not correspond to a universal temperature valid for all materials.
The formulas, with their conditions.
Q = m LL: latent heat in J/kg.
Use when: Given phase change, at the pressure and temperature conditions considered.
Where is this principle used?
Refrigeration and air conditioning plant
Exploit evaporation and condensation.
Foundry and thermal industry
Monitor melting, solidification and heat balances.
What to observe in the experiment
On a heating curve, separate the inclined portions of the bearings. Identify where the energy changes the temperature and where it changes the phase.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian