Amount of Propane Required to Melt 1L Aluminum

  1. I started off yesterday learning about specific heats, and measuring my ice cubes to figure out the correct number to cool my tea to a proper drinking temperature.

    Now today I was curious how much propane would be required to melt 1L of Aluminum since I'm also interested in casting Aluminum. I was hoping that someone could check my work, and then tell me how I can get more "Real world" results, or if this would even be practical at all for my level of math/physics/chem understanding.

    Also, if you have any concepts you think I should learn next I would appreciate any suggestions. I have some Physics, and Chemistry books that I am reading for furthering my education.

    Aluminum
    Latent Heat of Fusion: 398 J/g
    Specific Heat: 0.91 J/g°C
    Density: 2.70 g/cm^3
    Melting Point: 660.32°C
    Ambient Temperature: 20°C

    Mass of 1 Liter Aluminum (Mass = Density * Volume) (1mL = 1cm^3)
    2.70g/cm^3 * 1000mL = 2700g

    Required Energy for +640.32°C (Mass * Specific Heat * Temperature Difference)
    2700 * 0.91 * (660.32-20)
    2700 * 0.91 * 640.32
    2457 * 640.32 = 1,573,266.24

    1,573,266.24 J Required to Heat 20°C Aluminum to 660.32°C

    Required Energy to Change Solid -> Liquid (Mass * Latent Heat of Fusion)
    2700 * 398 = 1,074,600 J

    Total Energy to Heat, and Melt Aluminum (Raise Temp + State Change)
    1,573,266.23 + 1,074,600 = 2,647,866.23 J

    2,647,866.23 J
    735.5184 Wh (Joules/3600)
    2509.6929443 BTU (Joules/1055.05585262)

    Propane
    Molar Mass: 44.1g/mol
    Energy Density: 2220kJ/mol
    Liquid Density at 25°C: 0.493g/cm^3
    Mass Per Liter: 493g/Liter

    Moles Per Liter (Mass Per Liter/Molar Mass)
    493/44.1 = 11.17913832mols

    Energy Density per Liter (Mol * Energy Density)
    11.17913832 * 2,220,000 = 24817687.0704J

    Amount of Aluminum Melted per Liter of Propane (Energy per Liter Propane/Energy to Melt Aluminum)
    24817687.0704/2,647,866.23 = 9.3727118044L Melted per Liter of Propane
     
  2. jcsd
  3. Vanadium 50

    Vanadium 50 17,443
    Staff Emeritus
    Science Advisor
    Gold Member

    The first thing you could do to get more "real world" results is to use significant figures. 24817687.0704? Good heavens!
     
  4. mfb

    Staff: Mentor

    Well, in real setups, you don't get 100% efficiency. You will heat a lot of air and other parts of your experiment as well. The efficiency really depends on the setup.

    Working with units everywhere and with less [strike]in[/strike]significant figures would be useful.
     
  5. 9.372L of aluminum melted using just 1L of propane? Holy moly... Doing it for real will likely result in maybe 20-25% efficiency; you'd be lucky to be able to melt 3L with that much propane for real.
     
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