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Entropy-increases & decreases

  1. Mar 9, 2008 #1
    I am studying about entropy increasing and decreasing. I *think* I understand the example when liquid water is converted to ice, and that it demonstrates a decrease in entropy. However, I don’t get the other two – when solid sodium is dissolved in water and when hydrocarbons with 16 carbons are cracked into smaller hydrocarbons. Are they demonstrating an entropy increase or decrease? Why?
  2. jcsd
  3. Mar 9, 2008 #2
    Basically entropy signifies the number of states a system can be in. This means that when there are more particles in a system that the system can attain more states. So when solid sodium reacts with water to form sodium ions, hydrogen and hydroxide ions the system gains entropy because there will be more states for it to be in. When the hydrocarbon is cracked entropy also increases because there will be more particles in the system that can all be somewhere at some velocity which implies more states are available.
  4. Mar 10, 2008 #3
    Thanks for that wonderful explaination!! So they both demonstrate entropy increasing...I thought that is what it was, but now I have a better grasp on it - thanks to you:)
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