[lilianag]

Methyl isocyanate is a volatile highly toxic gas that killed thousands in india. If a 0.321 g sample of this gas is placed in a 1.500 x 10^2 ml sealed flask at 35.0 C and pressure 720.2 mmhg, determine the molar mass of methyl isocyanate.


Arsenic sulfide gas effuses at 0.4029 times the rate of effusion of Ar under the same conditions of temperature and pressure. Use this data to determine the formula of arsenic sulfide.


LASTLY,

A Mercury spill occurs in a lab whose temperature is 30.0 C. The vapor pressure of gaseous mercury at this temperature is 3.65 x 10^-6 atm. If the room has the dimensions (12.0 m long x 8.0 m wide x 3.00 m high, will the density of the mercury vapor in the room exceed the exposure limit of 0.050mg of mercury per m^3?

[sjb]

Methyl isocyanate is a volatile highly toxic gas that killed thousands in india. If a 0.321 g sample of this gas is placed in a 1.500 x 10^2 ml sealed flask at 35.0 C and pressure 720.2 mmhg, determine the molar mass of methyl isocyanate.


Arsenic sulfide gas effuses at 0.4029 times the rate of effusion of Ar under the same conditions of temperature and pressure. Use this data to determine the formula of arsenic sulfide.


LASTLY,

A Mercury spill occurs in a lab whose temperature is 30.0 C. The vapor pressure of gaseous mercury at this temperature is 3.65 x 10^-6 atm. If the room has the dimensions (12.0 m long x 8.0 m wide x 3.00 m high, will the density of the mercury vapor in the room exceed the exposure limit of 0.050mg of mercury per m^3?

What formulas do you know that may help?

[lilianag]

Some formulas I know are : for the first one: PV=nRt but I dont know how to obtain the volume? I mean someone gave me the answer of 5.71 g/mol but I do not know how to get to that...
for the second one: i am GUESSING that it is r1/r2=square root t1/t2
for the third one: i feel like it is D=PM/RT but i am not sure if my answer is correct....

[fledarmus]

For the first one, what is the size of the sealed flask that you have placed your sample in?

For the second one, I haven't seen those variables used, but the form of the equation looks right. Now which variables do you have values for?

[lilianag]

It does not say the size of the sealed flask, this is general chemistry 1 so it must be the usual flasks used in lab which are normal sized.
the second one...i do not know what you are referring to, i apologize :/

[fledarmus]

It does not say the size of the sealed flask, this is general chemistry 1 so it must be the usual flasks used in lab which are normal sized.

Really? See below...

sample of this gas is placed in a 1.500 x 10^2 ml sealed flask

[fledarmus]

For the second one, you have guessed the equation r1/r2=square root t1/t2 - what is r1? what is t1?

The reason I said the form is right is because it appears you might be trying for this:

http://en.wikipedia.org/wiki/Graham%27s_Law_of_Effusion

which is an appropriate starting point.

[lilianag]

Oh wow, I am making careless mistakes then, Excuse me please. Also, so for the first one the size of the flask is the volume then? not 0.321 g?
and for the second one my calculations are: rAs/rS= square root x/0.4029x..
but for the third one....how do I go about this problem?

[fledarmus]

yes, since you have a sealed flask, the volume occupied by the gas is the volume inside the flask. Grams (g) is a unit of mass, not volume.

The second one is still off. Let me clarify my questions - what does r1 represent in your equation? What does t1 represent? And what information are you given in the problem?

[lilianag]

then how do i find the molar mass? that is what confuses me... for the first one,
the second one....r stands for the rate of As / rate of S = square root time of argon/ 0.4029x (how fast it is going 0.4029 times?)

[fledarmus]

Back to the first one - you liked PV = nRT, what variables do you have so far? What are you missing?

For the second one, if t is time, then you are using the wrong equation. Go back and look at Graham's Law of Effusion. (Link shown in previous response). And think about what you are given, and what you are asked for - you are comparing a rate of arsenic sulfide effusion to a rate of argon effusion, you aren't comparing rates of arsenic to rates of sulfide. Arsenic sulfide will effuse as single molecules, not as separate atoms.

[lilianag]

P: 720.2 mmHg convert to atm it is:.9476 atm
V: 1.500 x 10^2 ml convert to L it is: 0.15 L
R: 0.0821 Lxatm/kxmol
T: 35.0C convert to K it is 308 K
n: ??
so in this case we use this formula: n=PV/RT
correct?
but n is the molar mass?
and the second one....
r1: the number of moles of AsS and r2: the number of moles of Ar and m1 is the molar mass of AsS and m2 is the molar mass of Ar...?