Lecture Notes for Sept. 4, 2008
Last Modified: 2011-07-04
Related Textbooks:Chemistry and Chemical Reactivity
Related Textbooks:Chemistry and Chemical Reactivity, Enhanced Review Edition (with General ChemistryNOW)
- One substance breaks down into two or more substances.
- C: 2(12.0 amu)
- + H: 6(1.0 amu)
- = 30.0 amu
- Ca: 1(40.1 amu)
- + Cl: 2(35.5 amu)
- = 111,1 amu
- do the C first, H second & O last.
- Formula Weight
- So the percentage of carbon ethane is:
- Sum of the atomic weights of the atoms in a molecule.
- So, the molecular weight for ethane, C2H6, would be:
- Rapid reactions that produce a flame.
- Most often involve
- How to balance combustion:
- Avogadro's Number (1776-1856), Italian
- 6.02 E23 (no unit)
- 18.0 amu of water = 1 mol H20
- Example = Aspirin = 180.2 g/mol
- One mole of atoms, ions, or molecules contains Avagadro's number of those particles.
- One mole of molecules or formula units contains Avagadro's number times the number of atoms or ions of each element in the compound.
- No unit, just a number.
- Comes from Carbon, the 12th Carbon.
- Percent Composition
- Subscripts and Coefficients
- Combination Reactions
- Decompositions Reactions:
- Combustion Reactions
- Law of Conservation of Matter:
- According to Coulomb's law, as the distance between ions decreases, the attractive forces
- As the ion charge increases the attractive forces
- %C = (2)(12.0 amu)/(30.0 amu) = 24.0 amu/20.0 amu x 100 = 80%
- Sum of the atomic weights for the atoms in a chemical formula
- So, the formula weight of calcium chloride, CaCl2, would be:
- These are generally reported for
- Two or more substances react to form one product.
- Equations must always be balanced.
- Lavoisier (1743-1794)
- Because the same atoms are present in a reaction at the beginning and at the end, the
- Matter can neither be created nor destroyed.
- Because of the
- Reactants appear on the left side of the equation.
- Products appear on the right side of the equation.
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