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Homework Help: Adding energy for enthalpies of formation by increasing velocity?

  1. Oct 25, 2006 #1
    I have no idea whether or not this is a ridiculous question, so I am just going to ask it.

    My question is based on the concept that energy must be added to ions to get them to form compounds (such as the formation of hydrogen iodide). Typically (or so my chemistry text book says), the addition of heat energy is the catalyst for these reactions. However, I also recently learned that light energy can also serve the role of catalyst (photochemical reactions). Can kinetic energy also somehow serve as a catalyst?

    Basically, can energy added to the system by means of increasing the systems velocity, thereby increasing the systems total kinetic energy, start a reaction?

    Feel free to call me an idiot if my question is ridiculous. I'm a physics major, not a chemistry major...haha.
    Last edited: Oct 25, 2006
  2. jcsd
  3. Oct 25, 2006 #2


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    I don’t think "catalyst" is really the right word to use for what you are describing.
    A catalyst lowers the activation energy of a compound, thereby increasing the rate of reaction without getting used up in the process.
    In the case of photosynthesis, the activation energy is provided by the light, and increasing the average kinetic energy of the substance (ie. raising its temperature) will also provide additional activation energy needed for the reaction to proceed.

    Increasing the reactants' kinetic energy is a way increase the likelihood of a chemical reaction occurring.
    For example...take two metal spheres, one made of Aluminum, the other made of Iron (rusted Iron). Place these two balls together and nothing will happen, the Aluminum and rust do not react. However, if you take these two balls in your arms and then slam them together fast enough you can create a small thermite reaction where the two spheres collide. The energy which went into starting the reaction originally came from the kinetic energies of the spheres before collision which was then turned into heat and allowed the substances to react.
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