DIR Return Create A Forum - Home
---------------------------------------------------------
Chemistry:The Central Science
HTML https://kolathechemist.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: Basics
*****************************************************
#Post#: 141--------------------------------------------------
chemistry Questions
DIR By: Kizitombano
Date: May 12, 2012, 2:40 pm
---------------------------------------------------------
the combustion of butane, Cs H12(12 down) in oxygen(air) is
present in the equation below
2C4 H10(a) +13O2(a) arrow 8Co2(g) + 10H2(g)
calculate the volume at the s.l.p needed to burn30cm cubed of
the butane..what will be the volume of oxygen if it is measure
at 10 degree C and 248mmHG pressure?
standard pressure=760 mmHG
standard temperature=0degree C
find the ration of the rate of diffusion of equal volumesof
methane and sulphur(iv) oxide through the same portion..
PLEASE I NEED ANSWERS AS SOON AS PSSIBLE..
#Post#: 142--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 12, 2012, 3:25 pm
---------------------------------------------------------
--- Quote from: Kizitombano link ---
>
>
> 2C4 H10(a) +13O2(a) arrow 8Co2(g) + 10H2(g)
>
>
>
>
--- End Quote ---
Avogadro's law states that 'equal volumes of gases at the same
temperature and pressure contain equal number of moles. This
means that for a gas, 'mole' may be substituted with 'volume'
From this equation, 13moles of O2 react with 2 moles of C4H10
meaning: 13cm3 of O2 will react with 2cm3 of C4H10
From this you see that 6.5cm3 of O2 reacts with 1cm3 of C4H10
if 6.5cm3 of O2 reacts with 1cm3 of C4H10,
How many cm3 of C4H10 will react with 30cm3 of O2 ?
Use this to find the volume of O2 at stp
Use general gas law to find the Volume at 10'C and 248mm
pressure
#Post#: 143--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 12, 2012, 3:35 pm
---------------------------------------------------------
For the second problem, Graham's law is suitable
r1/r2 =Square root of[M2/M1]
if we say
r1=rate of diffusion of CH4
r2=rate of diffusion of SO2
M1=Molar mass of CH4=16g/mol
M2=Molar mass of SO2
=96g/mol
r1/r2 is the ratio of their rates.
Find the sq. Root of 96/16
That gives the ratio of their rates
#Post#: 144--------------------------------------------------
Re: chemistry Questions
DIR By: Kizitombano
Date: May 12, 2012, 4:27 pm
---------------------------------------------------------
could you pls explain further...
tell me how to solve it mathematically...
#Post#: 145--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 12, 2012, 4:49 pm
---------------------------------------------------------
In the 1st problem,
A more detailed look at your equation shows that your equation
is slightly incorrect,
The products should read '4CO2+10H2O' not '4CO2+10H2'
Not that this affects the way you solve it...
As i said earlier,
6.5cm3 of O2 reacts with 1cm3 of C4H10
Meaning 1cm3 of O2 will react with 1/6.5 cm3 of C4H10
ie 1cm3 will react with ~0.1538 cm3 of C4H10
If 1cm3 of O2 reacts with 0.1538cm3, 30cm3 will react with
30*0.1538. Isn't it?
This gives the volume of 02 produced at stp.
To find the volume at 10'C and 248mmhg,
use the general gas equation. You can find that in your text
P1V1/T1 =P2V2/T2
V1 is the volume at stp (30*0.1538)
P1 is the pressure at stp (760mmhg)
P2 is the new pressure(248mmhg)
V2 is the volume you're looking for
Note: * represents multiplication
and / represents division
#Post#: 146--------------------------------------------------
Re: chemistry Questions
DIR By: Kizitombano
Date: May 12, 2012, 5:05 pm
---------------------------------------------------------
sorry to bother you...but please explain question 1 further..
#Post#: 147--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 12, 2012, 5:11 pm
---------------------------------------------------------
--- Quote from: Kizitombano link ---
>
> sorry to bother you...but please explain question 1 further..
>
--- End Quote ---
No problem:)
Please try to be more specific. Where exactly do you have
problems. What part of the solution should i explain further?
#Post#: 148--------------------------------------------------
Re: chemistry Questions
DIR By: Kizitombano
Date: May 12, 2012, 5:16 pm
---------------------------------------------------------
values for r1 and r2...and the si unit if the answer...
#Post#: 149--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 12, 2012, 5:25 pm
---------------------------------------------------------
--- Quote from: Kizitombano link ---
>
> values for r1 and r2...and the si unit if the answer...
>
--- End Quote ---
Your question didn't say we should find the values of r1 & r2.
It reads
--- Quote from: Kizitombano link ---
>
>
>
> find the ration of the rate of diffusion of equal volumesof
methane and sulphur(iv) oxide through the same portion..
>
>
>
>
--- End Quote ---
We want to find the ratio, not the values of r1 and r2
Since both r1 & r2 have the same SI unit, the units cancel out
and the answer has no unit
#Post#: 152--------------------------------------------------
Re: chemistry Questions
DIR By: Michel
Date: May 13, 2012, 5:59 am
---------------------------------------------------------
Please read reply#2 again, carefully...
I just edited it: sq. Root of 96/16 not the inverse, also
When you get your answer lets say a/b, express it in ratio form,
i.e a:b
*****************************************************
Page 1 of 2
DIR Next Page