Heat of Vaporization Hv of Water (Demonstration Lab)
Measure the Hv of water
Materials: See the diagram below.

Heat of Vaporization
Sketch by Ted Andersen, retired Physics Teacher at Brockport High, a teacher’s teacher!

1.  Mass the insulated cup, then the cup with water; record the starting temperature (0.1oC).
2.  Boil the water, bubbling "live" steam (100oC) into the insulated cup.
3.  Record the change in temperature of the water ΔT.
4.  Mass the cup with water again to determine the mass of the condensed steam.

1.  Calculate Hv using the equation for heat loss/heat gain (Qlost) = Qgained)
                    mw c ΔT   =  ms Hv  +  ms c ΔT                where ms is the mass of the steam only
                    (water)        (steam)     (steam)

2.  Determine the  % error.  What are some sources of error?
3.  Define Hv.
4. Why was it desirable to use steam at 1000C?
5.  Why did we start with water at approximately 100C?
6.  Describe some practical applications of water’s high Hv.

  Data Table
mass of cup_________           kg                   
mass of cup + water __________ kg
mass of water ______________ kg
temperature (cool)  __________ oC
temperature (hot) ___________ oC
Final temperature of water ______________ oC     
Temperature changes:   Condensate ______________oC,  Cold water______________oC
mass of cup + water + condensate _____________
mass of condensate (steam ms) ___________

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