1) Half Sheet: Write 3 things that you know about this image, 3 things you somewhat know, and 3 things you are having a difficult time with 2) Worksheet #6 3) QUIZ #3

2 Limiting Reactant A limiting reactant in a chemical reaction is the substance that Is used up first. Stops the reaction. Limits the amount of product that can form.

3 Reacting Amounts In a table setting, there is 1 plate, 1 fork, 1 knife, and 1 spoon. How many table settings are possible from 5 plates, 6 forks, 4 spoons, and 7 knives? What is the limiting item? Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

4 Reacting Amounts Four table settings can be made. Initially Use Left over plates 5 41 forks 6 42 spoons knives The limiting item is the spoon.

5 Example of Everyday Limiting Reactant How many peanut butter sandwiches could be made from 8 slices bread and 1 jar of peanut butter? With 8 slices of bread, only 4 sandwiches could be made. The bread is the limiting item. Copyright © 2008 by Pearson Education, Inc. publishing as Benjamin Cummings

6 Example of Everyday Limiting Reactant How many peanut butter sandwiches could be made from 8 slices bread and 1 tablespoon of peanut butter? With 1 tablespoon of peanut butter, only 1 sandwich could be made. The peanut butter is the limiting item. Copyright © 2008 by Pearson Education, Inc. publishing as Benjamin Cummings

7 Limiting Reactants When 4.00 mol H 2 is mixed with 2.00 mol Cl 2,how many moles of HCl can form? H 2 (g) + Cl 2 (g)  2HCl (g) 4.00 mol 2.00 mol ??? mol Calculate the moles of product from each reactant, H 2 and Cl 2. The limiting reactant is the one that produces the smaller amount of product.

8 Copyright © 2008 by Pearson Education, Inc. publishing as Benjamin Cummings

9 Limiting Reactants Using Moles HCl from H mol H 2 x 2 mol HCl = 8.00 mol HCl 1 mol H 2 (not possible) HCl from Cl mol Cl 2 x 2 mol HCl = 4.00 mol HCl 1 mol Cl 2 (smaller number) The limiting reactant is Cl 2 because it is used up first. Thus Cl 2 produces the smaller number of moles of HCl.

10 Checking Calculations InitiallyH mol Cl mol 2HCl 0 mol Reacted/ Formed mol mol Left after reaction 2.00 mol Excess 0 mol Limiting 4.00 mol

11 Limiting Reactants Using Mass If 4.80 mol Ca mixed with 2.00 mol N 2, which is the limiting reactant? 3Ca(s) + N 2 (g)  Ca 3 N 2 (s) Moles of Ca 3 H 2 from Ca 4.80 mol Ca x 1 mol Ca 3 N 2 = 1.60 mol Ca 3 N 2 3 mol Ca (Ca used up) Moles of Ca 3 H 2 from N mol N 2 x 1 mol Ca 3 N 2 = 2.00 mol Ca 3 N 2 1 mol N 2 (not possible) All Ca is used up when 1.60 mol Ca 3 N 2 forms. Thus, Ca is the limiting reactant.

12 Limiting Reactants Using Mass Calculate the mass of water produced when 8.00 g H 2 and 24.0 g O 2 react? 2H 2 (g) + O 2 (g) 2H 2 O(l)

13 Limiting Reactants Using Mass Calculate the grams of H 2 for each reactant. H 2 : 8.00 g H 2 x 1 mol H 2 x 2 mol H 2 O x g H 2 O g H 2 2 mol H 2 1 mol H 2 O = 71.5 g H 2 O (not possible) O 2 : 24.0 g O 2 x 1 mol O 2 x 2 mol H 2 O x g H 2 O g O 2 1 mol O 2 1 mol H 2 O = 27.0 g H 2 O (smaller) O 2 is the limiting reactant.

QUIZ #3 1) The limiting reactant is… A. the reactant that produces the least product B. the reactant that produces the most product C. the product that produces the least reactant D. the product that produces the most reactant 2) Given the following balanced equation below, what is the limiting reactant when 3 moles of KO 2 reacts with 3 moles of H 2 O? 4 KO H 2 O  4 KOH + 3 O 2 MUST SHOW WORK!!!