Can somone make the subject of limiting reagents easier for me?

[Rexus]

So I just recently started properly reading and studying into the science subjects, and up now is Chemistry. I am using Zumdahl's book as my crutch. I am somewhat confused on the issue of limiting reagents (under Stoichiometry) and was wondering if anyone could make it clearer. I googled it, and sites like Wikipedia made me somehow more confused.

 

http://en.wikipedia.org/wiki/Limiting_reagent

 

In the first example, why does it feel to me like a given was missing? And in the second example, where did we get the 157.9g from? Much thanks for the help.

[Ducky Havok]

In the first example they fail to give you the original balanced equation, or the fact that you start with 1.5 mol of benzene and 7 mol of oxygen. It seems to me like they just left out the question itself. And as for the 157.9 g/mol, that's the molecular weight of Iron (3) oxide (found from a periodic table).

 

As for the first part, do you not understand what a limiting reagant is, or just how to find one?

[Rexus]

Thanks for your reply. I don't understand how to find one. What I do know is that the limiting reagent is the reactant that's consumed first and thus it signals the end of the product sum that can be formed. Much thanks again.

[Borek]

Try this limiting reagent lecture.

 

Borek

--

equation balancer and stoichiometry calculator

[Cap'n Refsmmat]

The simplest way is to calculate how many moles of product will be formed for each reactant - so if you have x moles of H₂O, calculate how much product will be formed, and if the other reactant is HCl, and you have y moles, do the calculation again with that number.

 

The reactant that produces the lowest number is the limiting reactant.

 

Borek, please stop advertising (what I presume is) your site.