1 / 5

CHEM 433 – 9/9/11

CHEM 433 – 9/9/11. Introductory Topics B. Molecules and Energy (Ch. 0) - Definitions & Introductory comments - Energy Units - How do molecules Store energy? —> Quantization Read: Chapter “0” HW DUE Th – but start sooner than later. Basic Definitions re: “Molecules and Energy”.

keola
Download Presentation

CHEM 433 – 9/9/11

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. CHEM 433 – 9/9/11 Introductory Topics B. Molecules and Energy (Ch. 0) - Definitions & Introductory comments - Energy Units - How do molecules Store energy? —> Quantization Read: Chapter “0” HW DUE Th – but start sooner than later.

  2. Basic Definitions re: “Molecules and Energy” Working Definition of Physical Chemistry: “The study of the physical properties of matter, how these affect chemical change, and the interplay of energy with matter.” Matter: Atoms and molecules (also p+, n°, e-, quarks?, and all other “stuff”– anything w/ mass). Substance: A pure distinct form of matter. (i.e. all the atoms/ molecules are the same). Mole(s): Unit used to specify the amount of a substance(n).

  3. Basic Definitions re: “Molecules and Energy” • Avagadro Constant (NA): 6.02…x1023 mol-1; • —> The number of C atoms in exactly 12 g of 12C. • Intensive Properties are independent of n. (P, T, Density…). • Extensive Properties depend on n. (V, mass, entropy…). • (failure to understand the difference can have disastrous consequences: http://www.youtube.com/watch?v=zrzMhU_4m-g ) • Molar Properties: Extensive properties made to be intensive via division by n, i.e. (Xm = X/n). • Note: Only intensive properties can be characteristic. • Energy: Capacity to perform work. • **** Is energy intensive or extensive?

  4. How much energy is a C-C bond “worth” ? (i.e. how much energy is required to break it?) ~350 kJ/mol C C What is the value in…. kcal/mol ? J ? eV? cm-1? 83 kcal/mol 5.8 x10-19J 3.6 eV 29,000 cm-1

  5. Energy Quantization: The general Idea is that the smaller the particle, and the more tight its confines are, the larger the SPACINGS between ENERGY LEVELS… E E ~ 0 E ≥ kT E >>> kT i.e. large Puck in a rink Nuclei held by bonds e– held by nuclei

More Related