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Homework Help: Conservation of mass

  1. Sep 7, 2008 #1
    1. The problem statement, all variables and given/known data
    The conservation of Mass states that the total mass of substances is the same before and after a chemical or physical change occurs. Explain why this is true in yet not true of density. Explanations to include mathematical as well as verbal proofs.

    3. The attempt at a solution
    The law of conservation of mass, also known as Lomonosov-Lavoisier law, states that the mass of substances in a closed system will remain constant. Mass is neither created nor destroyed.
    I can't explain why this is true but i think i know why it is not true of density.
    Density = mass/volume
    if a solid square has 1*1*1 volume, and mass and changes to a rectangle. According to the law of conservation of mass the mass has to be same as the solid quare that has 1*1*1* volume and mass. but density cannot area changes and there for volume changes. Different density will come out if there is diffent volume but same mass.
  2. jcsd
  3. Nov 24, 2016 #2


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    Pretty much covers it.
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