thermal physics Flashcards
Q: What is specific latent heat of vaporization?
The energy required to change 1 kg of a substance from liquid to gas without changing temperature.
Can fusion and vaporization occur in reverse?
Yes, the same energy is released when freezing or condensing.
β
How can specific latent heat of vaporization be determined experimentally?
Use an electrical heater and a condenser to collect evaporated liquid.
Measure mass and use
πΌππ‘ =πΏπ
IVt=Lm.
How can specific latent heat of fusion be determined experimentally?
Use an electrical heater to melt ice.
Measure mass and use
πΌππ‘=πΏπ
IVt=Lm to find
πΏ
Why does vaporization require more energy than fusion?
Because the difference in internal energy between a gas and liquid is greater than that between a liquid and solid.
What is the method of mixtures for determining specific heat capacity?
Mix known masses of two substances at different temperatures.
Record temperature changes.
Use heat transfer equations to find
π
c.
How can specific heat capacity be determined more accurately?
By plotting temperature vs. time and calculating the gradient, using
π=πΌπ/(πΓgradient)
c=IV
How can uncertainties in the specific heat capacity experiment be reduced?
Use insulation to reduce heat loss.
Stir the liquid for even heating.
How can specific heat capacity be determined experimentally?
Heat a liquid in a vessel with a submerged heater and thermometer.
Measure mass, temperature change, and electrical power (I, V, t).
Use
πΈ=πΌππ‘=ππΞπ
E=IVt=mcΞΞΈ to find
π
How does electrostatic potential energy vary by phase?
Gas: 0 electrostatic potential energy
Liquid: Small negative electrostatic potential energy
Solid: Large negative electrostatic potential energy
Q: How can internal energy be increased?
A: By increasing temperature or changing phase (e.g., solid to liquid).
What is internal energy?
The sum of randomly distributed kinetic and potential energies of atoms or molecules within a substance.
Q: How does density generally change with phase?
A substance is most dense in the solid phase and least dense in the gaseous phase (except water).
How can Brownian motion be observed?
Using a smoke cell, where smoke particles move randomly due to collisions with air molecules.
What are the fixed points of the absolute temperature scale?
The triple point of water and absolute zero
What happens when two objects are in thermal equilibrium?
There is no net flow of thermal energy between them.
What is the triple point of a substance?
A specific temperature and pressure where all three phases of matter exist in thermal equilibrium.
