Lecture 11 Heating and phase changes

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Lecture 11 Heating and phase changes
2013-03-16 21:02:47
chem lecture 11 exam

this will be on exam 2 lec 11 chem
Show Answers:

  1. Equation for how much energy it takes to heat something up (VERY IMPORTANT!)
    Heat = mass x specific heat x temp
  2. Heat of fusion
    The quantity of heat required to completely  melt one gram of a substance once it has reached it's melting point.
  3. How do you determine heat of fusion and vaporization on heat curve?
    Look for the first horizontal, this will be heat of fusion or the change from solid to liquid, subtract the two. Same with vaporization except for it's the horizontal line from liquid to gas.
  4. Some velomobile seats have been designed to hold ice packs inside their cushions. If you started a ride with ice packs that held 1300 g of frozen water at 0 C and the temperature of the water at the end of the ride was 32 C how many calories of heat energy were absorbed? Heat of fusion 80 cal/g SH 1
    • Add together:
    • heat = mass (1300) x heat of fusion (80)= 104000
    • ¬†
    • heat = Mass (1300) x SH (1) x temp (32)= 41600
    • Answer is 104000 + 41600
  5. Sublimation
    The transformation from solid to gas
  6. Specific heat
    The amount of energy required to raise the temperature of one gram of a substance by 1 degrees celsius