3.4 Limiting Reactant Problems | General Chemistry

In this lesson Chad shows how to solve Limiting Reactant Problems. This includes how to determine the limiting reagent, how to determine the reagent in excess, and how much of the reagent in excess remains. It also includes how to calculate the theoretical yield, actual yield, and percent yield of a reaction as well.

Chad begins by showing how the coefficients in a balanced chemical reaction provide mole-to-mole ratios that are the basis of Limiting Reactant Calculations. These mole-to-mole ratios can then be used to convert moles of reactants to moles of products. Ultimately, whichever reactant would lead to the production of the least amount of product is the limiting reactant, while the others are the reactants in excess.

Chad begins with a practice limiting reactant problem involving bicycles to provide a more accessible example for students. The lesson then progresses to limiting reactant practice problems that involve starting with the number of moles of the reactants before moving on to limiting reactant problems that involve starting with the masses in grams of the reactants rather than the moles. The lesson concludes with a complex Limiting Reactant problem that includes how to determine the limiting reagent, how to calculate the theoretical yield, how to determine the amount of the reagent in excess that remains, and how to calculate the percent yield.

00:00 Lesson Introduction
00:47 Mole-to-Mole Ratios in Stoichiometry
09:44 Introduction to Limiting Reactant Calculations
13:15 Limiting Reactant Calculations
21:24 Percent Yield Calculations

[josphellihsilak]

From khan to Prof Dave and all the others, you're easily the best at teaching this material. Thank you.

[delonk]

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[chrismonzon]

Currently studying for the DAT and you make things so simple. I remember struggling with these concepts back in Gen Chem but your videos make these topics concepts look so easy. Wish I would have found your videos back in undergrad.

[tatendachemwaita]

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[jadenlim]

If only I had known about your bike analogy back in my high school chemistry classes, my friends and I wouldn't have to overthink as much haha, great video!

[Yehudisfasten]

I came into Chem not knowing my ass from my elbow. I was reall freaked out abt my first exam, but I recently got my grade back and I scored way above my expectations.all thanks to these videos

[rimurusensei]

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[aftabkim]

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[studentshir]

Thanks for this video! What if an example has multiple products and you are asked which one of the reactants is the limiting reagent? Should you pick any product to compare your reactants to?

[unokdr]

I use your method of calculating limiting Reagants which is using both reactants and figuring out which one produces the least product. Everyone else in my class uses the mole to mole ratio of both reactants to figure out how much of each reactant is needed and then figuring out which one of the reactants are less than what you need. Is there any difference between the 2 methods? Can I use the first method for all my examples?