Equilibrium. help please

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A closed, nonreactive system contains species 1 and 2 in vapor/liquid equilibrium. Species 2 is

a very light gas, essentially insoluble in the liquid phase. The vapor phase contains both species 1

and 2. Some additional moles of species 2 are added to the system, which is then restored to its

initial T and P. As a result of the process, does the total number of moles of liquid increase,

decrease, or remain unchanged?

 
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unchanged. it's insoluable in liquid so adding more would not increase the total number of moles in the liquid.
 
yeah i was thinking the same thing but the system is in equilibrium and needs to stay in equilibrium. i thought it was increase so that the mol/mol ration between vapor and liquid would remain 50/50. I talked to some kid and he said the TA said it was decrease, but gave no explanation.
 
i think by definition it has to. you're adding mass to the system. That mass should be distibured equally between the vapour and liquid

and this is like university thermodynamics dude.. try an engineering forum or something
 
no the liquid will increase because its in phase equilibrium with the liquid, since you added an excess of gas, some of that gas will change to liquid to preserve the eqilibrium, thus slightly increaseing the concentration of the liquid. maybe i think its been a year since i did chem 30
 
you would be surprised. they wouldn't tell you that for no reason. the answer is supposed to be decreasing. so its not as obvious as it seems. i just dont know how thats the answer.
 
Just to remind you... The liquid doesn't have to dissolve the gas for the gas to become liquid. They don't necessarily have to mix. I'd say its going to result in more liquid due to the fact that the system will naturally try to return to a lower pressure. You can basically just ignore the liquid species - if they're not reacting then it won't matter. And it's asking you if the moles of LIQUID increases or decreases... Not the moles of species 1/2.
 
decrease, because when you add species 2 none of it will become a liquid, but for the pressure and temperature to remain the same the volume of vapor has to be increased, therefore the volume of the liquid is decreased.
 
The number of moles in the liquid phase decreases (the teacher told me so).

Here is the reason why (I think): The system must adjust to the new equilibrium, which now contains more moles of species 2 in the vapor phase. The decrease in the total number of moles in the liquid phase is therefore a consequence of the addition of additional quantity. Even if species 2 is insoluble in the liquid phase, it does not mean that it will not become liquid; the system will attempt to return to a lower pressure to restore equilibrium. It is essential to be cautious since the question does not concern the increase in liquid of one species or the other but rather the increase or decrease in the total moles of the liquid phase.
 
The number of moles in the liquid phase decreases (the teacher told me so).

Here is the reason why (I think): The system must adjust to the new equilibrium, which now contains more moles of species 2 in the vapor phase. The decrease in the total number of moles in the liquid phase is therefore a consequence of the addition of additional quantity. Even if species 2 is insoluble in the liquid phase, it does not mean that it will not become liquid; the system will attempt to return to a lower pressure to restore equilibrium. It is essential to be cautious since the question does not concern the increase in liquid of one species or the other but rather the increase or decrease in the total moles of the liquid phase.
 
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