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Homework Help: The law of conservation of Matter [HELP]

  1. Oct 26, 2009 #1
    The law of conservation of Matter [HELP]!!

    What does conservation mean inthe context of matter. Explain please~!!
  2. jcsd
  3. Oct 27, 2009 #2
    Re: The law of conservation of Matter [HELP]!!

    Look at the law of conservation of energy. You can't create or destroy energy, only transform it.

    This means that the total energy of a system before something happens is the same as the total energy after.

    There's a similar idea with respect to matter. Basically the law states that the mass of a closed system will stay constant regardless of what is happening in that system. The significance of the closed system means that nothing can enter or leave. Everything is contained.

    So say you have the following reaction taking place inside a closed flask:

    C2H5OH + 3O2-> 3H2O + 2CO2

    It's a simple combustion reaction where ethanol is burned. If you put that flask on a mass balance and let the reaction happen, the mass would not change at all. Whatever mass of oxygen and ethanol you had (assuming it was all used) is equal to the mass of the water and carbon dioxide.

    If the system is open however, then this law does not apply because matter can come and go as it pleases.

    Does that help?
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