Blind Angel - 14-2-2004 at 09:05
An empty glass container has a mass of 658,57g. Once filled with nitrogen @ 790 torr and 15ºC, it mass is now 659,45g. When it his emptyed and
filled with another substance "A" @ 795 torr and 26ºC, it's mass is now 660,60g. The substance "B" is an organic gas made
from 85,6% of Carbone and 14,4% of Hydrogen is introduced in a container in inoxidable steel of 10,68L in presence of an oxcess of oxygene. The
container is then placed in a bath with a constent temp of 22ºC. The pressure is @ 11,98 ATM. In the container the is a container filled with
ascarite and an dessicative agent. Ascarite is a trademark of an soded amiante which suck up the CO2.
<center>NaOH<sub>s</sub> + CO<sub>2(g)</sub> ---> Na<sub>2</sub>CO<sub>3(s)</sub> +
<H<sub>2</sub>O<sub>(l)</sub></center>
The dessicative agent is magnesium perchlorate anhydrous, which absorb the water produced by the combustion reaction. Not the ascarite nor the
dessicative agent react in the substance "B" nor the O2. The total mass of the container, Ascarite and Dessicative agent included is
765,30g. The reaction is then initiated with a spark. The pressure grow up rapidly , then started the decrease and stabilise @ 6,02 atm. We open the
container in inoxidable steel and the mass of all that is included in is 846,70g. A and B react in a 1:1 ratio to form 1 mole of gaz "C".
a) Wht is the mass of C produced if 10.00L of "A" and 8,60 L of "B" @ normal pressure and temperature (101,3 kpa @ 24ºC) is
reacted in a linked system
b) what will be the total pressure of the system
This is what my chem teacher gave us as a bonus problem, i don't ask you the answer since i want to do it but it may be fun to do 
thunderfvck - 14-2-2004 at 11:14
Oh yeah, REAL fun. haha. I hate gas problems. This one is really nasty. Well probably not, I'm sure it's pretty easy once you start picking
out the details (like every other gas problem is easy). But the fact that it's two paragraphs makes me sick. And there's torr involved, a
unti I never used before...What's the conversion anyway? I could easily search for it, you don't have to answer me. heh. 1 atm = 101.3 kPa!!
I remember that. WHat's the gas constant again, like 8.03 blahs/blahblah*blah/blah or somethign?
Blind Angel - 14-2-2004 at 12:46
torr to kPa = 0.13332
R constant = 8.31
Btw i made some calc: i was able to answer the a) but can't find how to answer b) anyone has an idea
thunderfvck - 14-2-2004 at 13:16
I'm not positive, seeing as how I haven't delved into the problem myself. But shouldn't it just be the sum of the individual pressures
expressed by each gas? Hmmm, actually, I think you would have to find the total number of moles of gas in the system and solve for pressure.
I should also add that the total pressure of the system is the system as described in a).
[Edited on 14-2-2004 by thunderfvck]
[Edited on 14-2-2004 by thunderfvck]
t_Pyro - 16-2-2004 at 02:27
Quite easily done. Here's how I'd solve it: (The steps only, calculations not included)
p=pressure, v=volume, T=absolute temperature, n=no. of moles, m=mass of gas M=MW of gas
Initially, p, T, n (=m/M) of the nitrogen is know, so v of the container can be found out from pv=nRT
When gas A is used, p, T, v, and m are known, so M can be found out from pv=nRT again (M=m/n)
For gas B, p, v, and T are know, so knowing m, M can be found out. m is found out as follows:
%C in gas B=85.6
%H in gas B=14.4
so, mass of CO2 produced=((0.856*m)/12)*44
let this be equal to "x"
mass of H2O produced= ((0.144*m)/2)*18
let this be equal to "y"
now, x + y=gain in mass of combustion chamber. Replace the equations for x and y, and solve for m
There. Now that m is known, M for B can be found out.
In the reaction of A+B, find the no. of moles of A and B being used (using the values of M for A and B found out before). Find the no. of unreacted
moles of A or B (if any). Now, keeping in mind that A and B react in equimolar ratios, we know the total no. of moles of all the gases present after C
has formed. Since n, v, and T are known for this mixture, p can be found out.