Thur 12/3

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Thur 12/3 Regular Schedule

• Warm-up (do in your notebook)

Betty Crocker Chocolate Chip CookiesMakes 3
dozen1/3 cup Land O Lakes margarine 1/3 cup
shortening 1/2 cup sugar 1/2 cup light brown
sugar, packed 1 egg 1/2 tsp vanilla1 1/2 cups
flour1/2 tsp salt1/2 tsp baking soda 1 cup (6
oz) chocolate chipsBake at 375 degrees for 8-10
minutes. Cool on a wire rack. (taken from
http//www.recipelink.com/mf/2/17039 on 12/4/08)

• How much vanilla do you need to make 12 dozen
  cookies?
• How many cookies can you make with 30 oz of
  chocolate chips?
• How much sugar do you need if you use 6 cups of
  flour to make the cookies?

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Today. When youre making cookies, what
determines how many you can make? Whats the
limiting factor?
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Limiting Reagent

• aka Limiting Reactant
• The substance that makes the LEAST amount of
  product (limits the product)
• The substance the runs out first in a chemical
  reaction

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What if

• ......you bought these items new from the grocery
  store buying 1 package or container of each.
• Which item would limit the number of cookies you
  could make?

Betty Crocker Chocolate Chip CookiesMakes 3
dozen1/3 cup Land O Lakes margarine 1/3 cup
shortening 1/2 cup sugar 1/2 cup light brown
sugar, packed 1 egg 1/2 tsp vanilla1 1/2 cups
flour1/2 tsp salt1/2 tsp baking soda 1 cup (6
oz) chocolate chipsBake at 375 degrees for 8-10
minutes. Cool on a wire rack. (taken from
http//www.recipelink.com/mf/2/17039 on 12/4/08)
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Example 1

• Sodium chloride can be prepared by the reaction
  of sodium metal with chlorine gas.
• 2Na(s) Cl2(g) g 2 NaCl(s)
• Suppose you have 6.70 mol Na reacting with 3.20
  mol Cl2.
• What is the limiting reagent?
• How many moles of NaCl are produced?

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• 2Na(s) Cl2(g) g 2 NaCl(s)
• 6.70 3.20
• mol mol
• a) What is the limiting reagent?
• (Which one makes the least amount of NaCl?)

6.70 mol Na
2 mol NaCl
6.70 mol NaCl
Cl2 is the Limiting Reagent
2 mol Na
3.20 mol Cl2
2 mol NaCl
6.40 mol NaCl
1 mol Cl2
b) How many moles of NaCl are produced?
6.40 mol NaCl
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Example 2

• Copper sulfur are very different elements. When
  heated together the following occurs
• 2Cu(s) S(s) g Cu2S(s)
• What is the limiting reagent when 80.0 g Cu
  reacts with 25.0 g S?
• How many grams of Cu2S can be formed?

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• 2Cu(s) S(s) g Cu2S(s)
• 80.0 g 25.0 g
• a) What is the limiting reagent?
• (Which one makes the least amount of Cu2S?)

80.0 g Cu
100.9 g Cu2S
1 mol Cu2S
159.17 Cu2S
1 mol Cu
2 mol Cu
1 mol Cu2S
63.55 g Cu
25.0 g S
1 mol Cu2S
159.17 Cu2S
1 mol S
124 g Cu2S
1 mol S
1 mol Cu2S
32.07 g S
Cu is the Limiting Reagent
b) How many grams of Cu2S are formed?
100. g Cu2S
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Homework Due 12/4

• Limiting Reactant WS

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Before you go..

• Name
• Per
• Describe how to find the limiting reagent?