On a typical heating curve, what do the slopes represent?
The slopes represent the change in temperature as heat is added within a single phase (solid, liquid, or gas).
On a typical heating curve, what do the plateaus represent?
The plateaus represent phase changes (melting/freezing, boiling/condensation) where the temperature remains constant as heat is added or removed.
On a phase diagram, what area represents the solid phase?
The solid phase is generally located in the high pressure and low temperature region of the phase diagram.
On a phase diagram, what area represents the liquid phase?
The liquid phase is generally located in the moderate pressure and moderate temperature region of the phase diagram.
On a phase diagram, what area represents the gas phase?
The gas phase is generally located in the low pressure and high temperature region of the phase diagram.
Compare and contrast heating curves and cooling curves.
Heating curves: Endothermic, temperature increases with energy added, shows melting and vaporization. Cooling curves: Exothermic, temperature decreases with energy released, shows condensation and freezing. Both: Have slopes (temperature change) and plateaus (phase change).
Compare heat of fusion (Hโ) and heat of vaporization (Hโ).
Hโ: Energy to change solid to liquid. Hโ: Energy to change liquid to gas. Hโ is almost always greater than Hโ because all IMFs must be broken to vaporize.
Compare the processes occurring during the slopes versus the plateaus of a heating curve.
Slopes: Temperature changes, kinetic energy increases, q = mcฮT. Plateaus: Phase changes, potential energy increases (breaking IMFs), temperature remains constant, q = Hโ(m) or Hโ(m).
Differentiate between heat of vaporization and heat of condensation.
Heat of Vaporization: Energy absorbed when a liquid changes to a gas (endothermic). Heat of Condensation: Energy released when a gas changes to a liquid (exothermic); it's the negative of the heat of vaporization.
Differentiate between heat of fusion and heat of freezing.
Heat of Fusion: Energy absorbed when a solid changes to a liquid (endothermic). Heat of Freezing: Energy released when a liquid changes to a solid (exothermic); it's the negative of the heat of fusion.
Define 'heat of fusion' (Hโ).
The energy required for a substance to change from a solid to a liquid.
Define 'heat of vaporization' (Hโ).
The energy required for a substance to change from a liquid to a gas.
Define 'triple point' on a phase diagram.
The temperature and pressure at which solid, liquid, and gas phases coexist in equilibrium.
Define 'critical point' on a phase diagram.
The point beyond which a distinct liquid phase no longer exists; the substance becomes a supercritical fluid.
Define 'specific heat capacity'.
The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.
Define 'endothermic process'.
A process that absorbs heat from its surroundings.
Define 'exothermic process'.
A process that releases heat to its surroundings.
