During a chemical reaction the amount of each reactant will determine how much product is formed The limiting reagent is the reactant that is used up first in the reaction thus determining when the reaction stops ID: 652346
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Slide1
Limiting ReagentsSlide2
Limiting Reagents
During a chemical reaction, the amount of each reactant will determine how much product is formed.
The
limiting reagent
is the reactant that is
used up first
in the reaction, thus determining when the reaction stops.
The reactant that is not completely used up in the reaction is called the
excess reagentSlide3
Make a Ham and Cheese Sandwich
For example, let’s say you want to make ham and cheese sandwiches. You pull out all of your ingredients (ham, cheese, tomatoes, lettuce, and bread) and count how much you have of each.
Ingredient
Amount
Ham
12 pieces
Cheese14 piecesTomatoes7 piecesLettuce10 piecesBread28 pieces
6789
How many Sandwiches can you make?Slide4
Make a Ham and Cheese Sandwich
For example, let’s say you want to make ham and cheese sandwiches. You pull out all of your ingredients (ham, cheese, tomatoes, lettuce, and bread) and count how much you have of each.
Ingredient
Amount
Ham
12 pieces
Cheese14 piecesTomatoes7 piecesLettuce10 piecesBread28 pieces
HamCheeseTomatoLettuce
Which is the limiting reagent?Slide5
Make a Ham and Cheese Sandwich
For example, let’s say you want to make ham and cheese sandwiches. You pull out all of your ingredients (ham, cheese, tomatoes, lettuce, and bread) and count how much you have of each.
Ingredient
Amount
Ham
12 pieces
Cheese14 piecesTomatoes7 piecesLettuce10 piecesBread28 pieces
HamCheeseLettuceBread
-all of the above
Which ingredients are in excess?Slide6
Determining Limiting Reagent
Let's say that you were given 32 grams of H
2
and 160 grams of O
2
. Determine which reactant is the limiting reagent. Here is a general procedure to follow for finding limiting reagents: Put it in your notes….Key Idea: You use stoichiometry to figure out WHICH reactant will make the LEAST product!!That one reactant will run out first and limit the reaction.Slide7
Determining Limiting Reagent
Let's say that you were given 32 grams of H
2
and 160 grams of O
2
. Determine which reactant is the limiting reagent. Here is a general procedure to follow for finding limiting reagents: 1. Check to be sure you have a balanced equation ______H2 + ______O2 -----> ______H2OSlide8
Determining Limiting Reagent
Let's say that you were given 32 grams of H
2
and 160 grams of O
2
. 2 H2 + O2 2 H2O2. Convert the amount of the
first reagent that was given into moles of product.= _______ mol H2O_____________ x _______________Slide9
Determining Limiting Reagent
Let's say that you were given 32 grams of H
2
and 160 grams of O
2
. 2 H2 + O2 2 H2O2. Convert the amount of the
second reagent that was given into moles of product.= mol H2O____________ x _____________ x ___________Slide10
Determining Limiting Reagent
4. Determine which of the answers in step 2 and 3 produced the LEAST amount of product. The reactant that produced the LEAST amount of water is the limiting reagent.
2 H
2
+ O
2 2 H2O
160 g O2 X= 10.0 mol H2O32.0 g O21 mol O2 X 1 mol O22 mol H2O32 g H2 X= 16.0 mol H2O2.0 g H21 mol H2 x 2 mol H22 mol H2O