CHEM 121 Lecture Notes - Lecture 7: Molar Mass, Molecular Mass, Unified Atomic Mass Unit
Document Summary
The macroscopic view of chemistry is what we see. The microscopic view of chemistry is how we explain. Three important parts: skeletal equation, na + h2o -----> naoh + h2, stoichiometry coef cients: 2na + 2h2o ----> 2naoh + h2: a chemical equation is balanced, state symbols: 2na(s) + 2h2o(l) ----> 2naoh(aq) + h2(g: give physical form of participants, steps, write the skeleton equation, balance the least repeated element, then balance the more repeated element, add state symbols, example: 2c4h10 (g) + 13o2 (g) ----> 8co2 (g) + 10h2o (l) The microscopic view of chemistry = molecules and molecular mass. The macroscopic view of chemistry = moles and molar mass: molecular mass : the cum of atomic masses in the molecule, ex) so2, 1s = 32. 07 amu, 2o = 2 x 16. 00 amu, so2 = 64. 07 amu. For any molecule: molecular mass (amu) = molar mass (grams) Formula mass = the sum of atomic masses in formula unit.
