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Drill – 2/28/11 Sodium chloride decomposes into sodium and chlorine. How much (in grams) sodium chloride is required to produce 50.0g of chlorine gas?

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Presentation on theme: "Drill – 2/28/11 Sodium chloride decomposes into sodium and chlorine. How much (in grams) sodium chloride is required to produce 50.0g of chlorine gas?"— Presentation transcript:

1 Drill – 2/28/11 Sodium chloride decomposes into sodium and chlorine. How much (in grams) sodium chloride is required to produce 50.0g of chlorine gas?

2 Limiting Reagents

3 Example Your job is to attach arms on dolls in a doll factory. If you have 600 arms and 350 dolls, how many finished dolls can you make? What do you have in excess? What is limiting your production – the arms or the dolls?

4 Reagent –reactant in a chem reaction Limiting Reagent – the reactant that is completely consumed. This reactant limits the amount of product that is formed. Excess Reagent – the reactant that is not limiting the reaction. There will be leftovers of this reactant.

5 How to solve for limiting reagent 1.Write the balanced chemical equation 2.Determine the moles of each reactant 3.Determine how many moles of product each reactant would make using a mole ratio 4.The reactant that yields less product is the limiting reagent.

6 1.Write the balanced chemical equation Copper reacts with sulfur to form copper (I) sulfide. What is the limiting reagent when 80.0g Cu reacts with 25.0g S? CuS+  Cu 2 S2

7 2.Determine the moles of each reactant. Copper reacts with sulfur to form copper (I) sulfide. What is the limiting reagent when 80.0g Cu reacts with 25.0g S? 80.0 g Cu x 25.0 g S x 1 mole Cu 1 mole S g Cu g S = 1.26 mol Cu =.780 mol S

8 3.Determine how many moles of product each reactant would make using a mole ratio Copper reacts with sulfur to form copper (I) sulfide. What is the limiting reagent when 80.0g Cu reacts with 25.0g S? 1.26 mol Cu x.780 mol S x 1 mol Cu 2 S 2 mol Cu 1 mol S =.630 mol Cu 2 S =.780 mol Cu 2 S 1 mol Cu 2 S

9 4.The reactant that yields less product is the limiting reagent. Copper reacts with sulfur to form copper (I) sulfide. What is the limiting reagent when 80.0g Cu reacts with 25.0g S? Copper yields.630 mol Cu 2 S Sulfur yields.780 mol Cu 2 S So Copper is the limiting reagent

10 What is the excess reagent? How many moles of Cu 2 S will be produced?

11 Amount of Excess? In order to determine how much (mass) of excess reagents there are, you must figure out what mass of the excess reagent got used up…then subtract that from the initial mass.

12 Amount of Excess? Step 1 – Start with moles of product formed (from limiting reagent). Step 2 – Convert back to moles of excess reagent. Step 3 – Convert from moles to mass of excess reagent. Step 4 – Subtract this value from the original mass of excess reagent (given in problem)

13 Hydrogen fluoride reacts with aluminum oxide to produce aluminum fluoride and water. –If 60.0g of hydrogen fluoride react with 25.0g of aluminum oxide, how many grams of aluminum fluoride will be produced? –Determine the mass of excess reactant remaining.

14 Drill – 3/1/11 If 5.0g of hydrogen react with 9.0g of oxygen, what mass of water will be produced?


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