Amount of Energy Needed for Boiling a Litre of Water [closed]








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What is the amount of energy (J or Wh) needed to boil one litre of tap-water in a regular kettle starting at room temperature (20°C)?


The calculation itself assuming ideal and standard prerequisites would be interesting as well as factoring in the non-purity of tap-water and a typical kettle performance factor.




It is simple. Density of water is $1\;\frac{\text{g}}{\text{ml}}$ as we have 1 kg water.


Now according to the laws of calorimetry the amount of heat required



> 
> $Q = c \cdot m \cdot \left( {100{\text{ }^\circ\text{C}} - T} \right) + \Delta {h\_{\text{vap}}} \cdot m$
> 
> 
> 


Here 


* $c$ = specific heat capacity of water, which is 1 cal/(g °C)
* $m$ = mass of water; i.e. 1 kg
* $T$ = the room temperature in °C
* $\Delta {h\_{\text{vap}}}$ = specific enthalpy of vaporization of water; [540 cal/g](https://www.thermexcel.com/english/tables/vap_eau.htm)


So you will get the amount of energy needed (in cal) to boil a litre of water


To get answer in Joule multiply the answer in cal by 4.184 J/cal. And be careful with units!


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