chem-equilbrium
2011-01-09 5:12 am
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It has a gas syringe containing a pale brown mixture of N2O4(g) and NO2(g) at equilibrium at room temperature .
When the plunger is quickly pushed in, the gas first darkens and then lightens. Explain the observations.
(The temperature of the mixture is kept constant)
回答 (3)
2011-01-09 5:36 am
✔ 最佳答案
The gas first darken because the density of brwon gas getting higher, so the gas look darker quickly. After that, due to the equilibrium shift caused by the increse in pressure, a large part of brown NO2 convert to pale yellow N2O4, hence the colour of the gas lightened. 
2011-01-09 9:07 am
By PV = nRT, in this case, n,R,T are constant and thus when P is increased, the volume of gas is decreased.
So, the gas first darkens.
2011-01-09 01:07:50 補充：
Then, by Le Chatelier's Principle, the no. of moles of reactant is greater than that of the no. of moles of product and thus the equilibrium shifts to the right.
Finally, more product is formed.
The gas then lightens.
So, the gas first darkens.
2011-01-09 01:07:50 補充：
Then, by Le Chatelier's Principle, the no. of moles of reactant is greater than that of the no. of moles of product and thus the equilibrium shifts to the right.
Finally, more product is formed.
The gas then lightens.
2011-01-09 8:09 am
also mention Le Chatelier's Principle.
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