Unit IX  Gas Laws
Be able to solve problems using the combined gas law (Boyle’s, Charles’, GayLussac’s) and Dalton’s Law of Partial Pressure.
Be able to mass to volume or molarity to volume problems using the ideal gas law or Avogadro’s principle with the combined gas law.
Know the implications of Graham’s Law of diffusion.
Be able to do stoichiometry with excess and limiting reactants.

Terms:  ideal gas, STP, standard temperature, standard pressure, standard conditions, diffusion, Avogadro’s Principle, molar volume, limiting reactant, excess reactant, universal gas constant;  Old Terms:  molarity, molar mass, reactants, products, emperical formula, percent, temperature, pressure, moles, kinetic energy, potential energy.

Suggested Problems:  Read Chapter 18 & 19
    pgs 471-475 (27, 30-38, 40-47, 61, 65, 66)  Review (1-4, 7-9)
    pgs 494-497 (33-60)  Review (1-5)

In this unit we will be using the ideas of kinetic theory of gases to calculate amounts (stoichiometry) of gases involved in chemical reactions.  In past units we have learned how to calculate amounts of solids, liquids and solutions by measuring mass and using molar mass (grams/mole) or knowing the molarity (M, moles of solute/liter of solution).  Because the denisty of gases are so low it is difficult to measure the mass but it is reasonably easy to measure the volume.  Because the volume that a gas occupies is dependent only on the number of particles (moles), the temperature and the pressure (also easy to measure) we can determine the amounts of gases involved in chemical reactions.  (This only works well if the gas is not near its boiling - some would call it condensation - point.)  

In simpler terms, a student should be able to answer a question like: What volume of air (at 28% oxygen by volume) at 23°C and 1 atmosphere of pressure will it take to burn 125 grams of ethanol (one of the components of gasoline)?


To do these kinds of things the student will not only need to be able to calculate amounts using gas laws (PV=nRT for example) but will also need to write formulas, balance equations, calculate the number of moles from either mass or volume and molarity.