Stoichiometry

You may look at balanced chemical equations and find them cool and all, but not think much of it. After all, they seem simple in theory. However, you'd be surprised just how much you can learn out of the way two compounds or elements react with each other. Stoichiometry lets you delve deeper into the ratios and limitations that occur during chemical reactions. However, if you don't understand the concepts behind a mole yet, it is highly advised you check that out.

C + O → CO

Stoichiometry allows us to convert moles of one substance to moles of another using the reaction coefficients, which is super helpful. Confused? Let's take the reaction above. Let's say we have 15 moles of carbon atoms. Since the coefficient for carbon monoxide(CO) is 1 and the coefficient for carbon(C) is also 1, there is a 1:1 mole ratio between C and CO. This same principle applies to any two reactants/products in any chemical reaction.

Limiting Reactants

C + O → CO

Let's take this same reaction above and say we have an isolated chamber that can't interact with anything else. Let's say we put 15 moles of O in there and 24 moles of C in there. It may not seem like this at first, but in actuality, not al of the C will react. Remember that C and O react in a 1:1 ratio so every C reacts with an O. However, there's less moles of O than C, so what O would the C react with when those 15 moles are gone? Well, the remaining 9 moles of C won't react. This makes O what is known as a limiting reactant.


If you have a reaction and the actual ratio between the reactants(going left to right) is different from what is on the balanced equation, then you have a limiting reactant. Note that if you get masses, you need to use molar masses to figure out mole ratios specifically. To figure out what is the limiting reactant, just convert moles of reactants to moles of one of the products. The reactant whose conversion yields the least product is the limiting reactant.

Citations/Attributions

Chemistry 2e. Provided by: Openstax. Located at: https://openstax.org/books/chemistry-2e/pages/1-introduction. License: CC BY 4.0