Gas Stoichiometry Ideal Gas Law

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Gas Stoichiometry Ideal Gas Law

• Putting it all together

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Balance the following equation

• C8H18(l) O2(g) ? CO2(g) H20(g)
• 2 C8H18(l) 25 O2(g) ? 16 CO2(g) 18 H20(g)
• Coefficients of balanced equations can be used as
  mole ratios in stoichiometry problems

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Mass-Mass Stoichiometry

• Problem 11.13 c (p.332)
• Mg HCl ? H2 MgCl2
• 60.1 g HCl

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Volume Ratio Mole Ratio

• Problem 12.85 (p.373)
• 4 NH3(g) 5 O2(g) ? 4 NO(g) 6 H2O(g)

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Avogadros LawOne mole of a gas will occupy 22.4
L

• This means that the mole ratio is the same as the
  volume ratio

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Volume Ratio Mole Ratio

• Problem 12.85 (p.373)
• 4 NH3(g) 5 O2(g) ? 4 NO(g) 6 H2O(g)
• 200. L O2

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Volume Ratio Mole Ratio

• Problem 12.85 (p.373)
• 4 NH3(g) 5 O2(g) ? 4 NO(g) 6 H2O(g)
• Problem 12.81 (p.373)
• 2 C2H2(g) 5 O2(g) ? 4 CO2(g) 2H2O(g)
• 2.5 tanks O2

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Gas _at_ STP

• Problem 12.92 (p374)
• NaN3(s) Fe2O3(s) ? Na2O(s) Fe(s) N2(g)
• 6 NaN3(s) Fe2O3(s) ? 3 Na2O(s) 2 Fe(s) 9
  N2(g)
• 10.6 g NaN3

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Standard Molar Volume

• The volume of 1.0 mole of any gas at STP is 22.4
  L.
• This is called the standard molar volume.
• The volume of any gas at STP can be calculated if
  the number of moles is known
• V (moles)(22.4 L)

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Gas Not at STP

• Problem 12.88 (p.373)
• CaC2(s) 2 H2O(l) ? Ca(OH)2(s) C2H2(g)

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Ideal Gas Law

• All of the variables used to describe gases can
  be compared using the Ideal Gas Law
• The IGL is often called an equation of state, as
  it is very useful when finding some property of a
  gas at a certain condition
• Not so great when conditions are changing
• Entropy is another condition of state

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Ideal Gas Law

• PV nRT
• P pressure
• V volume
• T temperature
• n number of moles of gas
• R Gas Constant
• value depends on the desired unit

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Gas Constant (R)

• R is a constant that is used in the IGL so that
  it may be used for all gases
• It has a different value, depending on the
  pressure unit being used in the problem

8.314 LkPa 0.0821 Latm 62.4 LmmHg
8.314 molK 0.0821 molK 62.4 molk
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Gas Not at STP

• Problem 12.88 (p.373)
• CaC2(s) 2 H2O(l) ? Ca(OH)2(s) C2H2(g)
• 960 ml C2H2
• Problem 12.90 (p.373)
• 2 C8H18(l) 25 O2(g) ? 16 CO2(g) 18 H20(g)

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Gas Not at STP

• Problem 12.88 (p.373)
• CaC2(s) 2 H2O(l) ? Ca(OH)2(s) C2H2(g)
• 960 ml C2H2
• Problem 12.90 (p.373)
• 2 C8H18(l) 25 O2(g) ? 16 CO2(g) 18 H20(g)
• 837 L CO2