Which Graph?

Heat is being added to a sample of water at a constant rate. The water is initially solid, starts at -10°C and it takes 10 seconds to reach 0°C.

You may find the following data helpful when deciding which graph is correct:

Specific heats for water: cliquid = 1.0 cal/g °C and cice = csteam = 0.5 cal/g °C
Latent heats for water: heat of fusion Lf = 80 cal/g and heat of vaporization Lv = 540 cal/g

Which graph shows correctly the temperature as a function of time for the first 120 seconds?

  1. Graph 1
  2. Graph 2
  3. Graph 3
  4. Graph 4
  5. Graph 5
  6. None of the above