1. Chemistry – Chapter 14

2.  Kinetic Theory assumes the following concepts:  Gas particles don’t attract or repel each other  Gas particles are much smaller than the distances between them  Gas particles are in constant, random motion  No kinetic energy is lost when gas particles collide w/ each other or w/ the walls of their container  All gases have the same average kinetic energy at a given temp.

3.  Boyle’s Law states that the volume of a given amount of gas held at a constant temp. varies inversely w/ the pressure P 1 V 1 = P 2 V 2 P 1 and V 1 represent initial conditions; P 2 and V 2 represent new conditions  Charles’ Law states that the volume of a given mass of gas is directly proportional to its kelvin temp. at constant pressure V 1 = V 2 T 1 T 2  Temp. must be expressed in kelvin when using Charles’ Law Absolute zero – temp. that corresponds to zero volume Lowest possible theoretical temp. (O K) T K = 273 + T C

4.  Gay-Lussac’s Law states that the pressure of a given mass of gas varies directly w/ the kelvin temp. when the volume remains constant P 1 = P 2 T 1 T 2

5.  Combined gas law – Boyle’s, Charles’, and Gay-Lussac’s laws can be combined into a single law stating the relationship among pressure, volume, and temp. of a fixed amount of gas P 1 V 1 = P 2 V 2 T 1 T 2

6.  Avagadro’s principle – states that equal volumes of gases at the same temp. and pressure contain equal numbers of particles  Ex: 1000 relatively large Kr gas particles occupy the same volume as 1000 much smaller He gas particles  Molar volume – volume that one mole occupies at 0 0 C and 1 atm pressure  Standard temp. and pressure (STP) - 0 0 C and 1 atm  Avagadro showed that one mole of any gas will occupy a volume of 22.4 L at STP Conversion factor: 22.4 L 1 mol

7.  Ideal gas law – describes the physical behavior of an ideal gas in terms of the pressure, volume, temp., and number of moles of gas present PV = nRT  Where R represents the the ideal gas constant (Table 14-1)  Most common R value is 0.0821 L-atm/mol-K  In the real world, no gas is truly ideal  Most gases will behave like ideal gases at many temp. and pressure levels  Real gases deviate most from ideal gas behavior at very high pressures and low temperatures

8.  Applying the ideal gas law  Finding the molar mass of a gas sample: PV = m RT M Number of moles of a gas (n) is equal to the mass (m) divided by the molar mass (M) M = mRT PV  Finding the density of a gas: M = mRT = DRT PV P Density (D) is mass (m) per unit volume (v), therefore D can be substituted for m/V D = MP RT

9.  When gases are involved, the coefficients in a balanced chemical equation represent molar amounts AND relative volumes  Balanced chemical equations allow you to find ratios for moles and gas volumes only – not for masses  Temps must be expressed in kelvin