Easy Chem help

[xD_aQt]

I'm taking a break from Chemistry this month! I went hard out last month

[andy456]

Yeah I'm the opposite.... did nothing last month now gotta speed through it before school...

[andy456]

Got another question....

Iron metal is extracted in a blast furnace by a reaction between iron(III)oxide and carbon monoxide:
Fe2O3(s) + 3CO(g) -> 2Fe(l) + 3CO2(g)
To produce 1000kg of iron, calculate the volume of CO2 produced at SLC(25C and 101.3kPa)

[vexx]

^
i may as well attempt:)

n(Fe)=1,000,000/55.9
= 17,889mol
n(CO2)=(3/2) x n(Fe)
n(CO2)=26,883mol

Pv=NRT
v(CO2)=nRT/P
v=26883 x 8.31 x (25+273)/101.3
=655,975 L
sig figs: = 656 kL

[Potter]

^
i may as well attempt:)

n(Fe)=1,000,000/55.9
= 17,889mol
n(CO2)=(3/2) x n(Fe)
n(CO2)=26,883mol

Pv=NRT
v(CO2)=nRT/P
v=26883 x 8.31 x (25+273)/101.3
=655,975 L
sig figs: = 656 L

That looks good to me. Though, there's one thing I would've done differently.
Since it's at SLC conditions just multiply n(CO2) by 24.5, it's simple and reduces variables(which may lead to errors)

[vexx]

^ oh yeah i forgot about it being SLC! that's definitely a better way to do it.
but atleast mine way works with anything that isn't SLC or STP too

[crappy]

at SLC:

Volume=24.5 x n(?)

at STP:

Volume = 22.5 x n(?)


god, I hate chem

[fady_22]

Also, be careful with units: you said 656 L. Its 656 kL!

[Edmund]

Molar volume of an ideal gas:



where V_m is 22.4 L/mol or 24.5 L/mol depending on SLC or STP...

[vexx]

Also, be careful with units: you said 656 L. Its 656 kL!

oops- thanks for that! changed.

[andy456]

Just double checking for chemistry do you wait till the very end to round off... right???

[the.watchman]

Just double checking for chemistry do you wait till the very end to round off... right???

For an accurate answer, round off at the very end.
However, you can work through a question either 1 or 2 decimal places more than your final answer will be, that is OK.

[vexx]

Just double checking for chemistry do you wait till the very end to round off... right???

For an accurate answer, round off at the very end.
However, you can work through a question either 1 or 2 decimal places more than your final answer will be, that is OK.

yeah,
just keep everything on your calculator

so for example with calculating volume from a gas
find the mol
n=m/M
don't erase the calc !! if it was like 101.15949842 on the screen keep it.

then in the next equation
v=NRT/P
use what was on your calc to continue and times by N x R then dvide by P. then round off at final answer!

most calculations let you do this

[fady_22]

Just double checking for chemistry do you wait till the very end to round off... right???

For an accurate answer, round off at the very end.
However, you can work through a question either 1 or 2 decimal places more than your final answer will be, that is OK.

yeah,
just keep everything on your calculator

so for example with calculating volume from a gas
find the mol
n=m/M
don't erase the calc !! if it was like 101.15949842 on the screen keep it.

then in the next equation
v=NRT/P
use what was on your calc to continue and times by N x R then dvide by P. then round off at final answer!

most calculations let you do this

If your calculator doesn't do this, it would be a good idea to buy a new one.

[andy456]

What's a good calc for chem.... cause i have the casio classpad for methods which is great but i have been told i cant use that one in the chem exams