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Question on Endo/Exothermic reactions

  1. Nov 1, 2005 #1
    Hi, I was doing a small experiment in class today, which was on Endo and Exothermic reactions. Basically, the purpose of this expieriment was to find out which systems underwent exothermic or endothermic reactions. 3 systems had been tested, and here are as follows....
    1) Reaction between Steel wool and oxygen gas
    2) Reaction between Ammonium chloride and Water
    3) Reaction between "Drano" (a type of clog remover) and water

    1) - Temp of oxygen gas went up, and condensed
    2) - Temperature went slightly down, and the NH4 Cl was completely dissolved
    3) - Temperature went up, silver chunks of Drano turned black, and blue foams formed on top
    So this is all my data..
    My questions are, which ones are endothermic and exothermic reactions, and which ones are chemical and physical changes and why...
    Thanks in advance.
    Last edited: Nov 1, 2005
  2. jcsd
  3. Nov 1, 2005 #2
    Wow, I actually did this last year...that's a shocker.:rofl: If remember correctly...

    Endothermic- Describes processes that absorb heat energy.
    Exothermic- Describes processes that release heat energy.

    In exothermic reactions the temperature goes up, in endothermic reactions the temperature goes down.

    1. Exothermic
    2. Endothermic
    3. Exothermic

    Although, I'd have to suggest waiting to see what someone else says since I'm afraid to say "take my word for it".:tongue2:
  4. Nov 1, 2005 #3


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    Staff: Mentor


    An exothermic reaction would produce a temperature increase, an endothermic reaction a temperature decrease.

    There are three reactions here:

    1. Oxidation, the Fe wool ignites (oxidizes) in oxygen
    2. Dissolution - NH4Cl dissolves in water
    3. Hydration - anhydrous salt reacts with water

    Which one(s) is(are) chemical or physical, and why. Perhaps one can write the definition of chemical and physical reactions.
  5. Nov 2, 2005 #4
    Whoo! thanks a bunch guys, I hope I did well in my lab.. but hes gona be like: "Oh.. I dont like that font, 10% off....No hyphen there.. 20% off....and oh, another 45% off because I dont like you.." :'(
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