Chemistry Lecture September 2

Chemistry Lecture September 2 - Chemistry Lecture September...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemistry Lecture September 2, 2008 Chapter 3: Stoichiometry- Calculations with Chemical Formulas and Equations Law of Conservation of Mass Chemical Equations: Concise representations of chemical reactions Reactants appear on the left side of the equation Products appear on the right side of the equation The states of the reactants and products are written in parentheses to the right of each compound Coefficients are inserted to balance the equation Subscripts and Coefficients Give Different Information Subscripts tell the number of atoms of each element in a molecule Coefficients tell the number of molecules Reaction Types! Combination Reactions: 2 or more substances react to form one product (see examples in book) Decomposition Reactions: One substance breaks down into two or more substances Combustion Reaction o Rapid reactions that produces a flame o Most often involve hydrocarbons reacting with oxygen in the air Formula Weights!! Formula Weight (FW) Sum of the atomic weights for the atoms in a chemical formula So…the formula weight of Calcium Chloride, CaCl 2 would be Ca: 1(40.1 amu) +Cl: 2(35.5 amu) 111.1 amu Molecular weight (MW) Sum of the atomic weights of the atoms in a molecule For the molecule ethane, C 2 H 6 , the molecular weight would be … C: (12 amu) +H: 6 (1.0 amu)= 30.0 amu Percent composition- One can find the percentage of the mass of a compound that comes from each of the elements in the compound by using this equation: % Element = (number of atoms) (atomic weight)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

Chemistry Lecture September 2 - Chemistry Lecture September...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online