# A sample of #H_2O# with a mass of 46.0 grams has a temperature of 100 °C. How many joules are necessary to boil the water? (use 2.0934 J/g for the heat of vaporization of water)

##### 1 Answer

I get

(If I were to use your value, which is equal to

Sorry, but I refuse to use an incorrect enthalpy of vaporization. The correct value is

This can be found

Boiling a substance would be done at **constant pressure** and temperature, so we can *equate* the heat required with the enthalpy of vaporization:

#q = nDeltabarH_(vap)# where

#n# is the mols of liquid,#DeltabarH_(vap) = "40.67 kJ/mol"# , and#q# is the heat absorbed.

Thus, the heat absorbed is:

#color(blue)(q) = 46.0 cancel"g" xx cancel"1 mol"/(18.015 cancel"g") xx "40.67 kJ"/cancel"mol"#

#=# #color(blue)("104 kJ")#

or