Phase jumping&gases

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Phase jumping&gases

  1. 1. Tying up loose ends: Behavior of Gases Jumping Phase Evaporation is cooling
  2. 2. Endothermic vs. Exothermic • Anything Endothermic involves heat/energy entering the reaction/change • Anything Exothermic involves heat/energy exiting the reaction/change
  3. 3. So….. what’s so special about Gases? • What do gases do when they heat up? – Who can explain it?? (for a ticket!) • What do gases do when they cool down? – Who can explain it?? (for a ticket!) • What makes a hot air balloon rise? – Who can explain it?? (for a ticket!) • What would happen to a regular balloon if I blew it up and put it in the freezer? – Who can explain it?? (for a ticket!)
  4. 4. Jumping Phase!!!! • Sublimation – ENDOTHERMIC!! – Going from a solid to a gas- it skips the liquid phase altogether. – SO much energy is added that it goes straight to the last phase! – EX: Dry Ice • Deposition – EXOTHERMIC!!!! – Going from a gas straight to a solidit skips the liquid phase altogether! – SO much energy is taken away that it goes straight to the last phase! – EX: Snow!
  5. 5. Evaporation cools! • What did you learn from the Evaporation lab last week? – Evaporation is a cooling process! – As the liquid evaporates and becomes a gas, it has to get it’s energy from somewhere. So where does it get it from?
  6. 6. Evaporation cools! • Which of the liquids cooled the fastest? – Why do you think? – What does it have to do with density?
  7. 7. Evaporation cools! • Why do we sweat when we work out? – Why would our bodies do this? – What is the point?
  8. 8. Sublimation Lab • What did we learn yesterday? – Why was the CO2 white at first when it was coming off of the dry ice? – Was the CO2 more or less dense then air? How do you know? – Why did the dry ice sublimate faster in water than air? – And why was it faster in alcohol than water?

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