write out equation with mol values under reactants (products will be 0 mol initially)
question will tell you the mol value for one of the reactants at eqm.
The equation willl show you the ratio. (if 1:1 then the val at eqm will be the same if they have the same inital values)
Inital - eqm value = the volume of reactant used up.
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expression for an homogeneous system in eqm. 2
Look at ratio of products to reactants and use this to calculate vol of products
The question will tell the volume of the system. Divide the values of each volumes of products (a) and reactants (b) by the total volume of the system.
Kc = (a +a) / (b+b)
In some cases the units will cancel out and so Kc will have no units.
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Predicting effects of changes in temp and eqm cons
Type of reaction
endothermic with decrease in temp
Kc = decrease
Volume of products =decreases
Volume of reactants = increases
Eqm moves to the left.
endothermic with increase in temp
Kc = increase
volume of products = increases
volume of reactants = decreases
eqm moves to the right
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Predicting effects of changes in temp and eqm cons
exothermic with increase in temp
Kc = decrease
volume of products = decrease
volume of reactants = increase
eqm moves to the left
exothermic with decrease in temp
Kc = increase
volume of products = increase
volume of products = increase
volume of reactants = decrease
eqm moves to the right.
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General rule
For an exothermic reaction (enthalpy = -ve) increasing temp decrease eqm constant
For an endothermic reaction (enthalpy = +ve) increasing temp increases eqm constant.
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Changes in concentration or the addition of a cata
Concentration
addition to conc will cause eqm to remove changes to reduce disturbance
top and bottom values will change to produce the same values for Kc
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