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Natjack
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When I'm doing the Physics homework the problem for heat of vaporization uses Q=mcΔT and Q=mLv. How do I know when to use which equation through out the problem?
Yes.Natjack said:so use the mLv for phase changes?
The heat of vaporization is the amount of energy required to change a substance from its liquid state to its gaseous state at a constant temperature and pressure.
The heat of vaporization is affected by the type of substance, its temperature, and the pressure exerted on it. Generally, substances with stronger intermolecular forces will have a higher heat of vaporization, and higher temperatures and pressures will also increase the heat of vaporization.
The heat of vaporization is typically measured in units of energy per amount of substance, such as joules per mole or calories per gram. It can be experimentally determined by measuring the temperature change when a known amount of substance is vaporized at a constant pressure.
The heat of vaporization is important in many industrial and everyday processes, such as boiling water for cooking, distilling alcohol, and producing steam for power generation. It also plays a role in the Earth's water cycle, as water evaporates from bodies of water and later condenses to form precipitation.
No, the heat of vaporization is always a positive value because it represents the energy required to overcome the attractive forces between molecules and change the substance from a liquid to a gas.