Limiting Reagent If you have 20 wheels and 15 seats, how many bikes could you make? What will be in excess? How many pieces will be left over?
Limiting Reagent Limiting Reagent- this the reactant that will run out first and will determine the amount of product made (wheels) Excess Reagent- this reactant has more moles than can be used up in the reaction, this will leave some of the reactant not used (seats)
Limiting Reagent If you have 1 moles of AgNO 3 and 3 moles of Cu how many moles of CuNO 3 could you make? First step: write out the balance equation Second step: which is the Limiting Reagent? How do you know? Third step: use the limiting reagent to find the moles of CuNO 3 Fourth step: how much excess reactant will be left over?
Limiting Reagent If you have 3 moles of N 2 and 3 moles of H 2 how many moles of NH 3 could you make? First step: write out the balance equation Second step: which is the Limiting Reagent? How do you know? – Hint you need to consider the mole ratio! Third step: use the limiting reagent to find the moles of the product Fourth step: how much excess reactant will be left over?
Limiting Reagent If you have 100g of Na and 100g of Fe 2 O 3 how many grams of Na 2 O will be created? 6Na + Fe 2 O 3 → 3Na 2 O + 2Fe Second step: which is the Limiting Reagent? How do you know? – Hint you need to convert to moles then consider the mole ratio! Third step: use the limiting reagent to find the moles of the product Fourth step: how much excess reactant will be left over?
The Problem You are given 150 g of copper metal and 500 g of AgNO 3 and you combine them. Answer the following questions regarding that chemical reaction. AgNO 3 + Cu
Part I What kind of chemical reaction would this be? Will the reaction take place? How do you know? Give the balanced equation. AgNO 3 + Cu
Part II How many moles of each do we have to start with? What is the limiting reagent? What is the one in excess? 2AgNO 3 + Cu Cu(NO 3 ) 2 + 2Ag
Part III How much excess material do we have? How much of the limiting reagent material do we have left? 2AgNO 3 + Cu Cu(NO 3 ) 2 + 2Ag
Part IV How many moles of silver metal will be produced? How many grams of silver metal will be produced? 2AgNO 3 + Cu Cu(NO 3 ) 2 + 2Ag
Part V How many moles of copper nitrate will be produced? How many grams of copper nitrate will be produced? 2AgNO 3 + Cu Cu(NO 3 ) 2 + 2Ag
Part VI If we wanted to consume the rest of the excess material, how many more grams of the limiting reagent would we need to add? 2AgNO 3 + Cu Cu(NO 3 ) 2 + 2Ag
How many chocolate chip cookies can I make? Which ingredient will run out first!? How much excess materials will I have? I have in my pantry 6 eggs 12 cups of flour 27 oz of chocolate 6 cups of cane sugar 4 cups of butter 5 tsp of baking soda Yield ? I need for the recipe mol eggs 3.53 moles of flour 3.43 moles of chocolate mol of cane sugar moles of butter mol baking soda Yields 48 cookies
How many chocolate chip cookies can I make? Which ingredient will run out first!? How much excess materials will I have? I have in my pantry 6 eggs – mol 12 cups of flour – mol 27 oz of chocolate – 6.40 mol 6 cups of cane sugar – mol 4 cups of butter – 4.31 mol 5 tsp of baking soda – mol Yield ? I need for the recipe mol eggs – 1 egg 3.53 moles of flour – 3 cups 3.43 moles of chocolate – 16 oz mol of cane sugar – 1 cup moles of butter – 1 cup mol baking soda – 1 tsp Yields 48 cookies
Which ingredient will run out first? Sugar Vs Flour – Flour is LR Baking Soda VS Butter – Butter is LR Chocolate VS Egg – Chocolate is LR Flour VS Butter – Butter is LR Chocolate VS Butter – Chocolate is LR CHOCOLATE WILL RUN OUT FIRST!!!!!!
How to find Limiting Reagent Chocolate VS Butter First find moles of much I have of each 27 oz of c. ( g c.) ( 1 mol c) = 6.4 mol c. ( 1 oz) ( molar mass of c.) 4 cups of b. ( g b.) (1 mol) = 4.34 mol b. ( 1 cup) (molar mass of b.) ratio (have) ratio (need) 6.4 mol c = 1.47c to 1b 2.82 mol c = 2.6c to b 4.34 Mol b 1.08 mol b We need 2.6 chocolate for every 1 mol of butter, but we only have 1.47 mol of chocolate for every 1 butter = Chocolate is Limiting
How many cookies can I make? Hint: Start with the limiting reagent 6.4 mol chocolate ( 48 cookies) = 89 cookies ( 2.82 mol chocolate)