CHEM 5013 Applied Chemical Principles

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CHEM 5013 Applied Chemical Principles

• Chapter Three
• Professor Bensley
• Alfred State College

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Chapter Objectives

• Explain balancing a chemical reaction as an
  application of the law of conservation of mass.
• Write balanced chemical equations for simple
  reactions, given either an unbalanced equation or
  a verbal description.

3
Chapter Objectives

• Distinguish between electrolytes and
  non-electrolytes and explain how their solutions
  differ.
• Describe the species expected to be present
  (ions, molecules, etc.) in various simple
  solutions.

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Writing Chemical Equations

• What does a Chemical equation represent?
• Reactants form products

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Writing Chemical Equations

• Reactants and products are represented by
  chemical formulas.
• The phase for the compounds must be given.
• Example

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Balancing Chemical Equations

• The Law of Conservation of Matter (Conservation
  of Mass)

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Balancing Chemical Equations

• Chemical equations balanced via inspection.
• Numbers used to balance chemical equations are
  called coefficients.
• Example Burning of natural gas (methane)
  (Combustion Reaction)
• Example Write the complete balanced combustion
  reaction of propane.

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Balancing Chemical Equations

• We normally use the smallest whole numbers
  possible as coefficients.
• Trial and Error
• HINT Balance the atoms first that occur in only
  one substance on each side

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Balancing Chemical Equations

• DO NOT change the subscripts!
• BUT, if you have a polyatomic ion like SO42-
  (sulfate) this stays as one unit!!!
• So to balance, place a new subscript outside the
  parenthesis as in

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Balancing Chemical Equations

• Write balanced equations for
• Sodium hydroxide reacting with carbon dioxide to
  form water and sodium carbonate
• Sodium phosphate reacting with magnesium chloride
  to form magnesium phosphate and sodium chloride

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Solutions, Solvents, and Solutes

• Aqueous solutions
• Solutions (review)
• Solvent
• Solute

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Ions in Aqueous Solution

• Dissolve NaCl in water.
• Na ions and Cl- ions go into solution as freely
  moving ions
• What happens when you apply an electrical source
  (battery) to the solution?
• What about pure water?

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Electrolytes and Nonelectrolytes

• Electrolyte
• Examples

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Electrolytes and Nonelectrolytes

• Nonelectrolyte
• Examples

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Strong and Weak Electrolytes

• Strong electrolyte
• Example
• Weak electrolyte
• Example

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Solubility Rules

• Solubility -
• Soluble -
• Examples
• Insoluble -
• Examples

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Solubility Table

• Solubility guidelines - soluble salts

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Solubility Table

• Solubility guidelines - insoluble salts

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EXAMPLE

• Determine whether or not the following compounds
  are soluble or insoluble in water.
• 1) NaBr
• 2) Ba(OH)2
• 3) Calcium carbonate

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Chemical Equations for Aqueous Reactions

• When a covalently bonded material dissolves in
  water, what happens to the molecules?

NO IONS ARE FORMED!
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Chemical Equations for Aqueous Reactions

• When an ionic solid dissolves in water, what
  happens to the compound?
• This type of reaction is called a dissociation
  reaction.

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Molecular and Ionic Equations

• Remember chemical equations?
• When ions are involved, we can write them in
  three forms
• 1)
• 2)
• 3)
• Example
• Called metathesis or precipitate or double
  substitution reactions.

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Molecular and Ionic Equations

• Molecular Equation
• Complete Ionic Equation
• Net Ionic Equation
• Spectator Ions

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Example

• Write a net ionic equation for the molecular
  equations below
• KCl (aq) AgNO3 (aq) ? KNO3 (aq) AgCl (s)
• Potassium Chloride Calcium Hydroxide