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.

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?

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.

Try this limiting reagent lecture.

 

Borek

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equation balancer and stoichiometry calculator

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.