Chemistry Forums for Students > High School Chemistry Forum

Complecated Limiting Reactant Problems!

(1/3) > >>

chemhuff:
Hi...well, I sincerely say that I am NOT using this forum to get answers!  I've tried these problems a million times and can't understand them!  I know how to get the limiting reactant, its just the questions really confuse me!! >:(

1. I already balanced the equation:
Fe3O4 + 4H2 ---> 3Fe + 4H2O
Now here's the question: For the equation above, where 11.5g magnetic iron oxide is combined with .450 hydrogen gas, which substance is the limiting reactant?

I'M DUMBFOUNDED!!!! >:( ??? :-X
Here's the last one: (equation already balanced)
For the unbalance equation below, what mass of solid AgCl will precipitate from a solution of 1.50g CaCl2 with excess AgNO3?
CaCl2 + Ag NO3 ---> AgCl + Ca(NO3)2
PLEASE!  I SINCERELY ASK FOR *delete me*!  ...why do they have to make these questions confusing...urr

Mitch:
Tell me how many moles of Iron Oxide you have. Then tell me how many moles of Hydrogen you have.

chemhuff:
ok...forgive me if its wrong...i suck at this...for iron oxide, 27.82 mol (?) and for hydrogen 1.3 mol (?)  
I multiplied the atomic mass w/the number of atoms then divided it by one mole...is that wrong?

Mitch:
Lets look at your units.

Atomic weight = grams / mol

# of atoms = (atoms)

moles = moles.

Now this is what you did, you multiplied (grams/mol) and (# of atoms) = grams*#atoms/moles

Then you divided by moles, so the units of that is = grams*#atoms/moles2

That doesn't give you the units of moles, try again.

chemhuff:
ok....urr....is the mol for iron oxide 42.15?  and the mol for hydrogen 48.176?  1st, for iron oxide, I multiplied 3 atoms of iron times mole, then 4 atoms of oxygen times mole, and got a total of 42.15 mol for iron oxide.  Then I did the same for Hydrogen, 8 atoms*mole....GOD...i think i got it wrong again...

Navigation

[0] Message Index

[#] Next page