# Warm Up: Balance the below equation and answer the multiple choice question. ___H 2 + ___O 2  ___H 2 O 212.

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Warm Up: Balance the below equation and answer the multiple choice question. ___H 2 + ___O 2  ___H 2 O 212

Limiting Reagent

Limiting Reagent (Reactant) If you do a chemical reaction and one of the chemicals gets used up before the other one, the one that got used up is called the limiting reagent Controls the quantity of product

2 bread + 1 cheese = 1 grilled cheese

What is the limiting reagent? What is the theoretical yield (how many grilled cheese can I make)? cheese 2

Steps Check to be sure you have a balanced equation Convert the amount of each of the reagents into the amount of product that you could form if that reagent was completely consumed. Determine which of the answers produced the LEAST amount of product and that will be your limiting reagent. Also the LEAST amount of product will be your theoretical yield.

2 Al + 3 I 2 ------> 2 AlI 3 What is the limiting reagent and the theoretical yield if 108 g of Aluminum reacts with 635 g of Iodine? Aluminum= 108 g x 1 mol Al = 4 mol Al 27 g 4 mol Al x 2 mol AlI 3 = 4 mol AlI 3 2 mol Al Iodine = 635 g x 1 mol I 2 = 2.5 mol I 2 254 g 2.5 mol I 2 x 2 mol AlI 3 = 1.66 mol AlI 3 3 mol I 2

CuCl 2 +Na 2 NO 3  CuNO 3 + NaCl If 15 g of CuCl 2 reacts with 20 g of Na 2 NO 3 how much NaCl can be formed? What is the limiting reagent? 1CuCl 2 +1Na 2 NO 3  1CuNO 3 + 2NaCl

Cu163.5 Cl235.571 134.5 Na22346 N114 O31648 108

15 g CuCl 2 x 1 mol = 0.11 mol CuCl 2 134.5 g 0.11 mol CuCl 2 x 2 mol NaCl = 0.22 mol NaCl 1 mol CuCl 2 20 g Na 2 NO 3 x 1 mol = 0.185 mol Na 2 NO 3 108 g 0.185 mol Na 2 NO 3 x 2 mol NaCl = 0.37 mol NaCl 1 mol Na 2 NO 3

CuCl 2 = limiting reagent Theoretical yield= 0.22 mol NaCl

Excess 0.22 mol NaCl x 1mol Na 2 NO 3 2 mol NaCl 0.11 mol Na 2 NO 3 were used 0.185-0.11= 0.075 mol excess

For the following reaction, find the following: a)Which of the reagents is the limiting reagent? b)What is the theoretical yield of (NH 4 ) 3 PO 4 in grams ? 3 NH 4 NO 3 + Na 3 PO 4  (NH 4 ) 3 PO 4 + 3 NaNO 3 Assume we started with 30 grams of ammonium nitrate and 50 grams of sodium phosphate.

ammonium nitrate 18.6 grams of ammonium phosphate

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