destroyer Gchem#136

[baedero1]

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#136. at 0C, a gas is dissolved in water at a mole fraction of 2*10^-18. what is the molality of this solution given the molecular weight of the gas is 32g/mole.

the answer is 1*10^-16

I do not understand the calculation of solution. Can anyone explain this question?

 

[DDSguyLA]

im also unclear about this. can someone help out?

thanks

 

[happyasaclam88]

i came up with a solution, but it disregards the MM of the substance. is that a trick? what's the answer to the problem?

 

[joonkimdds]

This is a very very easy problem my friends~~~
mol fraction = mol of solute/mol of solution.
molality = mol of solute / kg of solvent.
These two are all you need to know.
I hope it helps 🙂 i will come back in couple of hours, i need to play some videogames now.

edit: if these hints are not good enough, i will write everything for you.
But first, i want you to try it with those two formulas I gave you.
and forget about Destroyer method of solving this problem. Use JoonKimDDS method 😀

 

[happyasaclam88]

i think you and i are doing the same thing, joonkimdds ... it's a bit of a trick question isn't it?

 

[joonkimdds]

i think you and i are doing the same thing, joonkimdds ... it's a bit of a trick question isn't it?

well... i don't think it's trick question. It's straight forward in my opinion.
I mean if a ******* like me think it's straight, it has to be damn straight 🙂

sorry but i am very sleepy now.
I will go to sleep, wake up and post my work.

edit: i will just do it now...before i go to bed. but i am very sleepy so maybe what i am about to say could be misspelled or etc.

mol fraction of gas = mol gas / mol total = 2 x 10^-18 = 2x10^-18mol gas / 1 mol total

at this point, 1 mol total means mol of gas + mol of water.

1 - 0.00000000000000000000000000000000002 is about 1 🙂
so we say mol of water is about 1.
now get kg of water and find molality.
1 mol of water = 0.018kg water

molality = mol of gas / kg of solvent.
= 2x10^-18mol gas / 0.018kg water


well...don't u agree that this is straightforward? not tricky~?
anyway i will see u guys tomorrow~