Familiarize yourself with the concept of heat of vaporization. Compare the heat of vaporization of different amounts of water with the energy required to heat the liquids.

### Heat of vaporization

The amount of energy required to vaporize of substance is called the heat of vaporization. Since the heat of vaporization depends on the temperature, the tables show the boiling heat of the substance, i.e., the heat of vaporization at the boiling temperature.

The amount of heat required for evaporation can be found using the formula

where is the heat of boiling and is the mass of the substance to be heated.

**The amount of water to be tested and the initial and final temperature**

Mass of water () | |

Initial water temperature ∘C | |

Final water temperature ∘C |

*The calculator calculates the amount of heat required for vaporization of substances or the amount of heat released during condensation. When using the calculator, enter the data in the table. The formula is used for calculation, where* *is the heat of vaporization of the substance and* *is the amount of water to be evaporated. The answer appears in the last row of the table.*

Heat of vaporization of substance | |

Mass | kg |

Evaporating/condensing the released amount of heat |
J |

### Boiling points and heats of vaporization of some substances

*The calculator calculates the amount of heat required to heat bodies from a substance or the amount of heat released when they cool down, using the formula* *. When using the calculator, enter the data in the table. The answer appears in the last row of the table.*

Specific heat of matter | |

Mass | kg |

Initial temperature | |

Final temperature | |

Temperature change | |

Internal energy change | J* |

* A negative result indicates that the internal energy of the body decreased. A positive result indicates that the internal energy of the body increased.

### Specific heats of some substances

**The heat required to heat and evaporate the amount of water**

Energy required to heat water | |

Energy required for water evaporation |

The heat of vaporization is high, even higher than the heat of fusion. So it is also very large compared to the amount of heat we need to heat liquids. To arrive at this recognition, the preceding calculation is useful. We also need to understand that compared to the time it takes to boil water on the stove, it takes a very long time to boil the water.