Before class on Sept. 7,
- Watch the 3 videos below (12 min, 7 min, 13 min);
- Comment or write a question or answer a question about 1 of them:
- Complete the note sheet found here: NOTES Lesson 3 Balance Equations, Stoich, Limiting Reactants as you watch the videos.
Intro to Limiting Reactants:
Limiting Reactant Problem (You can start watching this video around minute 1):
chemistry matters 
In these videos I learned how to use BCA tables to solve problems based on quantitative information given by a balanced equation, and how to use BCA tables to figure out which reactant (or reagent) is the limiting reactant and which is the excess reactant. The limiting reactant is all used up after the reaction is complete, and the excess reactant will have leftovers.
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Limiting reactant is the reactant that runs out first, which limits how much product can be made. The excess reactant is the reactant that does not run out, which mean there will be leftovers of it. When facing a limiting reactant problem, we use the BCA table (Before, Change, After) to figure out which reactant is the limiting/excess by testing out the mole require for each reactant when one is all use up during the Change phase. If the result make sense with the amount of each reactant we got (the mole require is not exceeding the amount that we have), then we know which reactant is limiting/excess when we do the calculation for the After phase.
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BCA tables allow us to determine limiting reactants. To do this, we must first change all grams into moles. When we ar finished, we usually change moles back into grams. When determining the glucose problem, why is H2O only 18 grams, instead of 18.02? is it because of the sig figs?
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Hi Amber, good question. The truth is I was tired and got sloppy at the end of the video :(. Since we had 3 sig figs in the measurement in the problem (1.00 g) I should have used at least 18.0 g H2O for the molar mass, or I could have used 18.02 g. I also should have rounded the final answer to 3 sig figs. If you try the problem both ways, you will see why the last digit is called the uncertain digit. If you use 18.0g, the answer rounds to 0.600g H2O. If you use 18.02g, the answer rounds to 0.601 g H2O. Both would be accepted as correct, because you last digit is your “uncertain digit”–therefore because of measurement uncertainty, you can’t really be sure if it is 0.600 g or .601g Either method is considered correct–you can use the correct number of sig figs all through the problem, or you can keep extra and just round at the end. I usually do the latter (except this time I forgot;) )
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In this lesson, I learned how to use BCA (before, change, after) tables. I also learned what limiting reactants and excess reactants are. Limiting reactants are the reactants that run out first and limit how much product can be made. Excess reactants are the reactants that don’t run out meaning there will be leftovers. You can tell that a problem is a limiting reactant problem because you are given two things.
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We use BCA tables to determine which reactant is the limiting reactant and which reactant is the excess reactant . A limiting reactant is the reactant that limits how much product can be made because it’s the one that runs out first. The excess reactant is the reactant that will not run out.
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In the following tutorials I learned how to use BCA tables for chemical reactions. You can only use moles for BCA tables. I also learned limiting reactants which is the reactant that runs out first and makes unable to make more products.
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Limiting Reactant is the reactant that is all used up first in the reaction. Because it is all used up, it determines how much of the product can be made. But the excess reactant is not all consumed during the reaction which means it has leftovers after the chemical reaction.
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In this video we learned about excess reactant and limiting reactant. we also learned how to figure out the amount of excess reactant..
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The limiting reactants are the reactants that get all used up.
The excess reactants are the leftovers reactants from the reaction.
I learned how to use the BCA tables to find out the limiting reactants, the excess reactants, as well as the products produced.
Why is it that the amount produced for each product is decided by the reactants’ corresponding number of moles?
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Since oxidation isn’t always combustion what else can it be and what are some examples?
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In these videos I learned about limiting reactants and excess reactants. We can use a BCA table for chemical formulas to determine the limiting reactants, excess reactants, or how much of a product is produced. When using the BCA table, it is important that we are using moles to aid in finding how much of a molecule/compound is left or produced.
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In the videos both limiting and excess reactants were explained. Both use quantitative information from balanced reactions to solve problems. A limiting reactant is a reactant that runs out first. It limits how much product can be made. An excess reactant does not run out, and there will be leftovers of the reactant.
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This video introduces the limiting reactants and excess reactants. Excess reactant can’t run out, and the limiting reactants determines how much it can be created.
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