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Entropy Calculator
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Entropy is related to probability. If a system has several states available to it, the one that can be achieved in the greatest number of ways is the one most likely to occur. That is the state with the greatest probability has the highest entropy.

Entropy Calculator calculates the entropy change for a chemical reaction.
 

Steps for Entropy Calculator

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Step 1 :  

List the given values for entropies in the problem.



Step 2 :  

Calculate the unkown entropy by substituting the given values in the entropy formula.


$\Delta$SReaction = $\Delta$SProducts - $\Delta$SReactants



Step 3 :  

Interpret whether the values of entropy is in specified units.



Problems on Entropy Calculator

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  1. Calculate the entropy change for the following reaction.

    PCl5 $\rightarrow$ PCl3 + Cl

    Given that

    $\Delta$SPCl3 + Cl2 = 122J/K/mole

    $\Delta$SPCl5 = 98J/K/mole


    Step 1 :  

    Given Data


    $\Delta$SPCl3 + Cl2 = 122J/K/mole


    $\Delta$SPCl5 = 98J/K/mole



    Step 2 :  

    $\Delta$SReaction = 122 - 98


    $\Delta$SReaction = 24J/K/mole



    Step 3 :  

    The enthalpy change of the reaction is given in J/K/mole units.



    Answer  :  

    The enthalpy change of the given reaction is 24J/K/mole.



  2. Predict the entropy change wheteher it is positive or negative for the followig reaction.

    2NOCl $\rightarrow$ 2NO + Cl2


    Step 1 :  

    The reactant side contains only 2 moles where the product side has 3 moles produced.



    Step 2 :  

    $\Delta$SReaction = $\Delta$SProducts - $\Delta$SReactants


    $\Delta$SReaction = 3 - 2 = 1 J/K/mole



    Step 3 :  

    The entropy chenge in this reaction is given by 1 J/K/mole.



    Answer  :  

    The change in entropy is positive in this reaction and it is given by 1 J/K/mole.



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