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Can someone feed me the bone of it? I really hate this thing, I have no idea how it works. I read Wikipedia, watched Youtube videos, read the chapter in my Chem book, and listening to my teacher ramble about it for hours... Yet I can't get it.

It's based off the fact that you can convert moles of one substance to moles of another and also you can convert any other unit from/to moles. So if you have grams of one thing, convert it to moles, look at the coefs in the chemical equation which relates moles, then convert it to moles of your second, unknown, substance. It's a lot easier to explain if you give a problem.

SM-Count wrote:It's based off the fact that you can convert moles of one substance to moles of another and also you can convert any other unit from/to moles. So if you have grams of one thing, convert it to moles, look at the coefs in the chemical equation which relates moles, then convert it to moles of your second unknown substance. It's a lot easier to explain if you give a problem.

+1

sometimes i just dont understand the point of +1 posts =.=

anyways i hate stoichiometry, its annoying and we keep getting the same questions over and over again, but yeah sm's summary is indeed a good summary

magisuns wrote:anyways i hate stoichiometry, its annoying and we keep getting the same questions over and over again, but yeah sm's summary is indeed a good summary

Easy points man.

Cruor wrote:

magisuns wrote:anyways i hate stoichiometry, its annoying and we keep getting the same questions over and over again, but yeah sm's summary is indeed a good summary

Easy points man.

easy points of continuous boredom tho =P

SM-Count wrote:It's based off the fact that you can convert moles of one substance to moles of another and also you can convert any other unit from/to moles. So if you have grams of one thing, convert it to moles, look at the coefs in the chemical equation which relates moles, then convert it to moles of your second, unknown, substance. It's a lot easier to explain if you give a problem.

Follow this advice. It's correct.

Furthermore, almost all stoichionetry questions follow the same steps, so as long as you understand the basics (moles/grams convertion), then you should be able to do harder questions. Also, make sure you know how to identify which of the reagents is your limiting reagent (just because reagent X = 0.50 mole and reagent Y=1.00 mole, it doesn't mean X is the limiting reagent... you gotta look at the balanced reaction provided).

It's based on blabla's law that states that in a closed system no matter will be lost during a chemical reaction.

Thus each atom you start with will be present at the end.


AB + CD <=> AD + BC

Some example

(Na)2SO4(aq) + Ba(NO3)2(aq) ==> NaNO3(aq) + BaSO4(s)

As you can see you have more sodium and nitrate ions on the left than on the right side of the equation. Thus you need to balance it to:


Na2SO4(aq) + Ba(NO3)2(aq) ==> 2NaNO3(aq) + BaSO4(s)
=
1 mole of sodiumsulfate reacts with 1 mole of bariumsnitrate to give 2 moles of sodiumnitrate and 1 mole of bariumsulfate.

I'm quite sure bariumsulfate doesn't dissolve thus the above equation should be correct.

Next example:

Ca3(PO4)2(aq) + HCl(aq) => CaCl2 + H3PO4

After balancing you get

Ca3(PO4)2(aq) + 6HCl(aq) => 3CaCl2 + 2 H3PO4
=
1 mole of calciumphosphate reacts with 6 moles of hydrochloric acid to yield 3 moles of calciumchloride and 2 moles of phosphoric acid.

U have to calculate how much u gotta have of one thing to react with something else.
For this u gotta have as much, or more atoms/molecules.
u could calculate it by knowing how much one neutrone/protone weighs but it's easier by doing it with moles.
1 mole = 6,023 x 10^24 atoms/molecules (correct me if I'm wrong?) that's just a number like a dozen or w/e.
u don't need that number actually, it's just an amount, u calculate the mole by mass/relative atom mass (if it's a molecule it's the sum of all atom mass), that's in ur table of mendelejev.
and if u wanna get a reaction work, make sure the moles are the same, or more.
That's it basicly lol, i can explain mole/l and mass% too but I think u get the point by now^^

takolin wrote:It's based on blabla's law that states that in a closed system no matter will be lost during a chemical reaction.

Thus each atom you start with will be present at the end.


AB + CD <=> AD + BC

Some example

(Na)2SO4(aq) + Ba(NO3)2(aq) ==> NaNO3(aq) + BaSO4(s)

As you can see you have more sodium and nitrate ions on the left than on the right side of the equation. Thus you need to balance it to:


Na2SO4(aq) + Ba(NO3)2(aq) ==> 2NaNO3(aq) + BaSO4(s)
=
1 mole of sodiumsulfate reacts with 1 mole of bariumsnitrate to give 2 moles of sodiumnitrate and 1 mole of bariumsulfate.

I'm quite sure bariumsulfate doesn't dissolve thus the above equation should be correct.

Next example:

Ca3(PO4)2(aq) + HCl(aq) => CaCl2 + H3PO4

After balancing you get

Ca3(PO4)2(aq) + 6HCl(aq) => 3CaCl2 + 2 H3PO4
=
1 mole of calciumphosphate reacts with 6 moles of hydrochloric acid to yield 3 moles of calciumchloride and 2 moles of phosphoric acid.

isn't this mister blabla called Avogadro.

maxietheboss wrote:

takolin wrote:It's based on blabla's law that states that in a closed system no matter will be lost during a chemical reaction.

Thus each atom you start with will be present at the end.


AB + CD <=> AD + BC

Some example

(Na)2SO4(aq) + Ba(NO3)2(aq) ==> NaNO3(aq) + BaSO4(s)

As you can see you have more sodium and nitrate ions on the left than on the right side of the equation. Thus you need to balance it to:


Na2SO4(aq) + Ba(NO3)2(aq) ==> 2NaNO3(aq) + BaSO4(s)
=
1 mole of sodiumsulfate reacts with 1 mole of bariumsnitrate to give 2 moles of sodiumnitrate and 1 mole of bariumsulfate.

I'm quite sure bariumsulfate doesn't dissolve thus the above equation should be correct.

Next example:

Ca3(PO4)2(aq) + HCl(aq) => CaCl2 + H3PO4

After balancing you get

Ca3(PO4)2(aq) + 6HCl(aq) => 3CaCl2 + 2 H3PO4
=
1 mole of calciumphosphate reacts with 6 moles of hydrochloric acid to yield 3 moles of calciumchloride and 2 moles of phosphoric acid.

isn't this mister blabla called Avogadro.

Nope

Lavoisier defined the law of conversation of matter/mass and it states that mass can't be lost during the reaction.
The other 2 laws are the law of definite proportions by Proust that says that a chemical compound always contains the exact same proportion of elements by mass. EG oxygen takes up 8/9th of the mass of pure water and hydrogen 1/9th. The lawt of multiple proportions from Dalton states that elements always combines in ratio of smallwhole numbers.

i think its easy balance equation stuff. maybe with mole ratio. just read your book more time s and if you still dont get it, go ask teacher for help, teachers have better advice than us faceless ppl

well thanks guys, one of my classmates tutored me a bit and i think i get it a little more now... but not completely. i hate chemistry.

ThatBluePerson wrote: i hate chemistry.

Shun the non-believer.
SHUUUUN
SHHHHHHHUUUUUUUUNNNNAH

easiest chem test i ever took was on stoichiometry... wait until limiting reactants w/ stoichiometry!

yeah we started to scrape the surface of limiting reactants...

this is going to be my test tomorrow, can someone do it for me

Stoichiometry = easiest part of chemistry (and most logical, IMO)


Shouldn't give you trouble. >_>

Draquish wrote:Stoichiometry = easiest part of chemistry (and most logical, IMO)


Shouldn't give you trouble. >_>

It's more math than chem imo.