Chapter 5 Chemical Reactions and Quantities

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Chapter 5Chemical Reactions and Quantities

• Mole Relationships in Chemical Equations

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Mole-Mole Factors

• Show the mole-to-mole ratio between two of the
  substances in a balanced equation
• Use the coefficients of two substances in the
  equation

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Writing Mole Factors

• 4 Fe 3 O2 2 Fe2O3
• Fe and O2 4 mole Fe and 3 mole O2
• 3 mole O2 4 mole Fe
• Fe and Fe2O3 4 mole Fe and 2 mole Fe2O3
• 2 mole Fe2O3 4 mole Fe
• O2 and Fe2O3 3 mole O2 and 2 mole Fe2O3
• 2 mole Fe2O3 3 mole O2

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Learning Check S1

• 3 H2(g) N2(g) 2 NH3(g)
• A. A mole factor for H2 and N2 is
• 1) 3 mole N2 2) 1 mole N2 3) 1
  mole N2
• 1 mole H2 3 mole H2 2
  mole H2
• B. A mole factor for NH3 and H2 is
• 1) 1 mole H2 2) 2 mole NH3 3) 3
  mole N2
• 2 mole NH3 3 mole H2 2 mole
  NH3

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Solution S1

• 3 H2(g) N2(g) 2 NH3(g)
• A. A mole factor for H2 and N2 is
• 2) 1 mole N2
• 3 mole H2
• B. A mole factor for NH3 and H2 is
• 2) 2 mole NH3
• 3 mole H2

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Chemical Calculations

• 4 Fe 3 O2 2 Fe2O3
• How many moles of Fe2O3 are produced when 6.0
  moles O2 react?
• 6.0 mole O2 x 2 mole Fe2O3 4.0 mole Fe2O3
• 3 mole O2

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Learning Check S2

• 4 Fe 3 O2 2 Fe2O3
• How many moles of Fe are needed to react with
  12.0 mole of O2?
• 1) 3.00 mole Fe
• 2) 9.00 mole Fe
• 3) 16.0 mole Fe

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Solution S2

• 4 Fe 3 O2 2 Fe2O3
• 12.0 mole O2 x 4 mole Fe 16.0 mole Fe
• 3 mole O2

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Learning Check S 3

• 4 Fe 3 O2 2 Fe2O3
• How many grams of O2 are needed to produce 0.400
  mole of Fe2O3?
• 1) 38.4 g O2
• 2) 19.2 g O2
• 3) 1.90 g O2

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Solution S 3

• 2) 19.2 g O2
• 0.400 mole Fe2O3 x 3 mole O2 x 32.0 g O2
• 2 mole Fe2O3 1 mole O2
• 19.2 g O2

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Mass of A Reaction

• The reaction between H2 and O2 produces 13.1 g
  of water. How many grams of O2 reacted?
• Write the equation
• H2 (g) O2 (g) H2O (g)
• Balance the equation
• 2 H2 (g) O2 (g) 2 H2O (g)

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• Organize data
• mole bridge
• 2 H2 (g) O2 (g) 2 H2O (g)
• ? g 13.1 g
• Plan g H2O mole H2O mole O2
  O2
• Setup
• 13.1 g H2O x 1 mole H2O x 1 mole O2 x 32.0
  g O2 8.0 g H2O 2 mole H2O 1 mole O2
• 11.6 g O2

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Points to Remember

• 1. Read an equation in moles
• 2. Convert given amount to moles
• 3. Use mole factor to give desired moles
• 4. Convert moles to grams
• grams (given grams (desired)
• moles (given) moles (desired)

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Learning Check S 4

• How many grams of O2 are need to react 50.0
  grams of Na in the reaction
• 4 Na O2 2 Na2O
• Complete the set up
• 50.0 g Na x 1 mole Na x ________ x _______
• 23.0 g Na

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Solution S 4

• 4 Na O2 2 Na2O
• 505 g Na x 1 mole Na x 1 mole O2 x 32.0 g
• 23.0 g Na 4 mole Na 1 mole O2
• g O2

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• Learning Check S5
• Acetylene gas C2H2 burns in the oxyactylene
  torch for welding. How many grams of C2H2 are
  burned if the reaction produces 75.0 g of CO2?
• 2 C2H2 5 O2 4 CO2 2 H2O

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Solution S5

• 2 C2H2 5 O2 4 CO2 2 H2O
• 75.0 g CO2 x 1 mole CO2 x 2 mole C2H2 x 26.0 g
  C2H2
• 44.0 g CO2 4 mole CO2
  1 mole C2H2
• 22.2 g C2H2

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Pathways for Problems Using Equations

• Given (A) Find (B)
• grams (A) grams (B)
• moles (A) moles (B)
• particles (A) particles (B)

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Pathways for Problems Using Equations

• Given (A) Find (B)
• grams (A) grams (B)
• molar molar
• mass (A) mass (B)
• coefficients
• moles (A) moles (B)
• Avogadro's
  Avogradros
• number number
• particles (A) particles (B)