Chem Ppl

[decypher]

aww man, if this was 5 years ago i could help u out... cuz in chem 11 i was some what responsible and understand how to do that, but then i turned to trading calculator games, thowing stuff, passing out on the desk and smoke breaks, and forgot it all... but good luck... u can always drop the course and get a study block like i did in grade 12

[pbreak]

Originally posted by NeVeRLooKBacK
hahaha
my chem prof has two of those mole things
and he named them too!!

chem teachers are such dorks...

[NeVeRLooKBacK]

oh yea
you gotta love the jokes they dish out too

[Pussy_Kat]

awe thank you
ok hold on
propane burns in air according to the equation: C3H8+5O2 --> 3CO2+4H2O

if 10.0 g of propane and 10.0 g of oxygen gas are reacted find which is in excess and by how much

a) number of moles of C3H8
b) number of moles of O2
c) dividing by tho coefficiants gives:
C3H8= O2=
d) LImiting reagent is C3H8 or O2?
e) number of moles C3H8 or O2 is needed to use up all of the O2 or C3H8?
f) number of moles C3H8 or O2 is left over?
g) number of grams C3H8 or O2 is in excess?

[pbreak]

Originally posted by Pussy_Kat
awe thank you
ok hold on
propane burns in air according to the equation: C3H8+5O2 --> 3CO2+4H2O

if 10.0 g of propane and 10.0 g of oxygen gas are reacted find which is in excess and by how much

a) number of moles of C3H8
b) number of moles of O2
c) dividing by tho coefficiants gives:
C3H8= O2=
d) LImiting reagent is C3H8 or O2?
e) number of moles C3H8 or O2 is needed to use up all of the O2 or C3H8?
f) number of moles C3H8 or O2 is left over?
g) number of grams C3H8 or O2 is in excess?

g if that's what your askin

[pbreak]

The limiting reagent is simply the one NOT in excess - correct me if im wrong ( im going to do some calculations) , the molar mass (i.e. g/mol) simply = the atomic mass unit (i.e. for Carbon = 12g/mol)... i don't have a book on me and don't do this shit at work

[Pussy_Kat]

k i got that the O2 is the limiting so the C3H8 is in excess
and i just minus the two moles from eachother to get the moles left over then converty it back into grams then minus them from eachother to get the grams in excess
but i dont understand the whole dividing the coefficients part
thats what i dont get

[Moon]

wow... chem was actually my best subject in highschool but i've forgotten EVERYTHING! shiiiiiet this is a wake up call to get back to the chem 12 notes if i wanna take chem 101... shiet

[pbreak]

i don't really understand what you're getting at with that step either - whatever molecule has more mols (i.e. more molecules) is in excess - you also know by how many mols it's in excess so it should be simple to convert it back to grams

[pbreak]

that's all you need to do... that is the answer is it not?

[pbreak]

Originally posted by NeVeRLooKBacK
oh yea
you gotta love the jokes they dish out too

Two hydrogen atoms are in a bar (really small bar i guess). The one hydrogen atom says:

"Dude, i think i lost my electron!"

The second one asks "Are you sure?"

First - "I'm positive!"

[NeVeRLooKBacK]

thats pretty much it
you'll know the number of moles in excess and then you can convert it back in to grams with the molar mass of the compound

[Pussy_Kat]

hahah ^ ok
no it says dividing by the coefficients gives:
C3H8?
O2?
WTF DOES THAT MEAN

[NeVeRLooKBacK]

Originally posted by pbreak


Two hydrogen atoms are in a bar (really small bar i guess). The one hydrogen atom says:

"Dude, i think i lost my electron!"

The second one asks "Are you sure?"

First - "I'm positive!"

those are the ones

[pbreak]

Originally posted by Pussy_Kat
hahah ^ ok
no it says dividing by the coefficients gives:
C3H8?
O2?
WTF DOES THAT MEAN

coefficient is just math jargon for some number you already came up with (probably just the g/mol of the molecule or some shit) and if you came up with the amount of C3H8 in grams that wasn't used you got the answer and at some point divided by the coefficients. I'm gonna actually do this at home and let you know exactly which ones they mean

[Pussy_Kat]

OMFG im soo lost
:soak: :soak: :soak: :soak: :soak: :soak: :soak:
:finger: :finger: :finger: :finger: :finger: :finger: :finger:
FCK U CHEM

[pbreak]

the C3H8 is in excess by 7.25g - is this what you got?

[NeVeRLooKBacK]

this is nothing
wait till you balance redox reactions in acid base situations
hahaha
those are a bitch

[Pussy_Kat]

haha to bad im not taking chem antymore
hahaha
my exam is wed
and i dont know what im doing
its that fcking question with the coefficients
which are the balancing number (the number in front ) but i don tknow what to do

[pbreak]

Originally posted by Pussy_Kat
hahah ^ ok
no it says dividing by the coefficients gives:
C3H8?
O2?
WTF DOES THAT MEAN

ok, i think they're just talkin about the number in front of the molecules in the equation (i.e. the 5 infront of 5O2) - that sounds like a stupid way of teaching things, but i really need to see whats goin on in your book

[crookedking]

Originally posted by stringbeans
hah i hated chem.. all i did was play calculator games in that class

this was the only post i understood.

lol i can spell boobless!

[kozmo_jr]

pBreak
^^wow your damn smart, i never knew you were a chem wiz!

[pbreak]

k - here is my solution:

C3H8: 3(12) + 8(1) = 44g/mol
O2: 2(16) = 32g/mol

10g * 1/44 mol/g = 0.2272727272.... mol
10g * 1/32 mol/g * 1/5 (coefficient!!) = 0.0625 mol

subtract the two to get: 0.164.... mol of C3H8 in excess

0.164 mol * 44 g/mol = 7.25g of C3H8

[Pussy_Kat]

WTF????
:finger: :finger: :finger: :finger:
Damn this all to hell!
k i didnt get that
im good till the fcking coefficient part then i got lost and messed up the entire question

[sNyx]

Oh man, last night I was SOOOO dox'd.
Back out tonight to redox.. woot!