the temperature of ice remains at 0°C even though we are heating till the all the ice gets converted into water this is due to *
Latent heat of vaporization
latent heat of fusion
Condensation
Melting
Answers
Explanation:
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Lumen
Boundless Physics
Heat and Heat Transfer
Phase Change and Latent Heat
Latent Heat
The latent heat is the energy associated with a phase change of a substance.
LEARNING OBJECTIVES
Describe the latent heat as a form of energy
KEY TAKEAWAYS
Key Points
Energy is required to change the phase of a substance, such as the energy to break the bonds between molecules in a block of ice so it may melt.
During a phase change energy my be added or subtracted from a system, but the temperature will not change. The temperature will change only when the phase change has completed.
The heat Q required to change the phase of a sample of mass m is given by
Q
=
mL
f
(melting or freezing) and
Q
=
mL
v
(evaporating or condensing), where Lf and Lv are the latent heat of fusion and the latent heat of vaporization, respectively.
Key Terms
latent heat of fusion: the energy required to transition one unit of a substance from solid to liquid; equivalently, the energy liberated when one unit of a substance transitions from liquid to solid.
latent heat of vaporization: the energy required to transition one unit of a substance from liquid to vapor; equivalently, the energy liberated when one unit of a substance transitions from vapor to liquid.
sublimation: the transition of a substance from the solid phase directly to the vapor state such that it does not pass through the intermediate, liquid phase
Latent Heat
Previously, we have discussed temperature change due to heat transfer. No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings.
image
Melting Icicle: Heat from the air transfers to the ice causing it to melt.
Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart so that the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature. Similarly, energy is needed to vaporize a liquid, because molecules in a liquid interact with each other via attractive forces. There is no temperature change until a phase change is complete. The temperature of a glass of lemonade initially at 0 ºC stays at 0 ºC until all the ice has melted. Conversely, energy is released during freezing and condensation, usually in the form of thermal energy. Work is done by cohesive forces when molecules are brought together. The corresponding energy must be given off (dissipated) to allow them to stay together.
The energy involved in a phase change depends on two major factors: the number and strength of bonds or force pairs. The number of bonds is proportional to the number of molecules and thus to the mass of the sample. The strength of forces depends on the type of molecules. The heat Q required to change the phase of a sample of mass m is given by
Q
=
mL
f
(melting or freezing)
Q
=
mL
v
(evaporating or condensing)
where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.
image
Phase Transitions: (a) Energy is required to partially overcome the attractive forces between molecules in a solid to form a liquid. That same energy must be removed for freezing to take place. (b) Molecules are separated by large distances when going from liquid to vapor, requiring significant energy to overcome molecular attraction. The same energy must be removed for condensation to take place. There is no temperature change until a phase change is complete.
Heating and Phase Changes of Water: A graph of temperature versus energy added. The system is constructed so that no vapor evaporates while ice warms to become liquid water, and so that, when vaporization occurs, the vapor remains in of the system. The long stretches of constant temperature values at 0ºC and 100ºC reflect the large latent heat of melting and vaporization, respectively.
Answer:
the temperature of ice remains at 0°C even though we are heating till the all the ice gets converted into water this is due to *
Latent heat of vaporization
latent heat of fusion
Condensation
Melting