Post on 31-Dec-2015
© 2005 Mark S. Davis
Law of Conservation of Mass
• Mass is neither created nor destroyed in chemical reactions– Lavoisier
© 2005 Mark S. Davis
Chemical equations
• Tell you: – What has – What – Ratio of – Products, reactants– Conditions
© 2005 Mark S. Davis
Balancing equations
• Why?– To show conservation of mass– Keep proper amounts of reactants and
products– Show proper ratios between products
and reactants
© 2005 Mark S. Davis
Types of reactions
• Combustion
• Synthesis (Combination)
• Decomposition
• Single Replacement
• Double Replacement
© 2005 Mark S. Davis
Combustion Reactions
• Fuel – Carbon compound
• Ignition source – flame
• Oxygen source
© 2005 Mark S. Davis
Synthesis Reaction
• Reaction of two substances to form one product
• Either elements or compounds react to form one compound as product
• Generally:
© 2005 Mark S. Davis
Decomposition Reaction
• One compound breaks apart to form two or more other elements or compounds.
• Generally:
• Sodium azide
© 2005 Mark S. Davis
Single Replacement
• Reaction of an element and a compound to form two new substances
• Generally:
• Zinc and Copper sulfate
© 2005 Mark S. Davis
Double Replacement
• Two solutions react to form two or more new substances
• Generally:
• Lead (II) nitrate and potassium iodide
• Identify the solid, gas, liquid, aqueous components
© 2005 Mark S. Davis
• http://dbhs.wvusd.k12.ca.us/webdocs/ChemTeamIndex.html
• http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Equations.html
© 2005 Mark S. Davis
Average Atomic Mass
• Average mass of all the isotopes of an element– 98.5% C-12– 1.5% C-13
© 2005 Mark S. Davis
Formula Weight
• The sum of the masses of all the atoms in a compound.
• Usually refers to – –
© 2005 Mark S. Davis
Avogadro’s Number
• The number of particles in one mole of a compound
• 6.022 x 1023 particles in one mole
© 2005 Mark S. Davis
Empirical Formulas
• Simplest formula
• C6H12O6 can be reduced to
• Represents the
© 2005 Mark S. Davis
Empirical Formulas
• Ethylene glycol, the substance used in automobile antifreeze, is composed of 38.7% C, 9.7% H, and 51.6% O by mass. Its molar mass is 62.1 g/mol. What is the empirical formula? What is the molecular formula?
© 2005 Mark S. Davis
Empirical Formulas• Caproic acid, which is responsible
for the foul odor of dirty socks, is composed of C, H, O. Combustion of 0.225 g of caproic acid produces 0.512 g CO2 and 0.209 g H2O. What is the empirical formula of caproic acid? If it has a molar mass of 116 g/mol, what is the molecular formula?
© 2005 Mark S. Davis
Problem
• Determine the empirical formula of a compound that has the composition of 20.20 % magnesium, 26.60 % sulfur, 53.20 % oxygen.
© 2005 Mark S. Davis
Problem 2
• It was determined that a compound was made from 43.66 % P and 56.34 % O, what is the empirical formula?
© 2005 Mark S. Davis
Molecular Formulas
• Represents the formula of the actual molecule
• If the empirical formula is CH2O and the molar mass is 120 amu, what is the molecular formula?
© 2005 Mark S. Davis
Early Stoichiometry
• Stoichiometry Steps for success online
• Method of converting