08-Jun-2012

Knowledge Statements

1. A chemical reaction involves the production of new chemical species, in general this involves a reorganization of the valence electrons into new configurations (bonds)
2. A phase change does not involve bond breaking, but rather changes in intermolecule interactions. The identify of the substance is conserved.
3. Many chemical reactions can be placed in common classes (such as redox, acid-base, and nucleophile / electrophile reactions); these can be understood in terms of the organization of valence electrons of the atoms and molecules involved.
4. We use different models to describe acid-base reactions, each more general than the previous. The Bronsted-Lowry model is often used for reactions in which protons are transferred in aqueous solution. The Lewis acid-base model is more general.
5. Energy changes in reactions can be understood (in part) in terms of the energies involved in bond breaking and bond formation.
6. A full understanding of a reaction requires a consideration of entropic factors as well.

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Performance expectations:

• Construct models to represent and analyze and differentiate between chemical and phase changes.
• Explain how a molecule’s structure leads to acidic and/or basic properties. Predict and explain relative strengths of a range of related acids (or bases).
• Construct models of strong, weak, dilute or concentrated acids and bases.
• Explain how the progression of Arrhenius, Bronsted-Lowry, and Lewis acid-base theories builds on each other.
• Use the curved arrow notation to predict the products of acid base reactions.
• Using relatively acid base strengths of products and reactants, predict the relative extents of acid-base reactions.
• Calculate pH from given concentrations of strong (ie completely ionized) acids or bases. Use pH to calculate [H₃O+] or [–OH]
• Explain how to distinguish between an acid base and redox reactions.
  Use bond energies to predict and calculate enthalpy changes in reactions.