Compressed gasses and the Ideal gas law Lesson 5

Compressed gasses Gasses are incredibly important as they support life and serve many other functions. Gasses that have pressures higher than atmospheric pressure are also very useful as they are used in many aspects of daily life. Ex. Tires, propane tanks, propellants.

The handling of pressurized gasses is incredibly important as they can have the same chemical hazards that other materials have. They can be corrosive, toxic, flammable and dangerously reactive. Unlike other materials they have the potential of becoming rockets.

Don’t copy Scuba divers also face risks when they dive. If their regulator does not match the pressure that the diver is experiencing at that instant with the air it is releasing. The diver could suffocate or they could burst their lungs.

The Ideal Gas Law

Ideal gas – A hypothetical gas composed of particles that have zero size, travel in a straight line, and have to attraction to each other. (zero intermolecular forces) The ideal gas law combines Boyle’s and Charles’ law with Avogadro’s mole. This gives us the formula.

Where P = pressure, V = Volume, n = moles, T = temperature in Kelvin and R The constant R in this equation is known as the universal gas constant.  The universal gas constant has a value which depends only upon the units in which the pressure and volume are measured.   8.3143510  J/mol K or   8.3143510  kPa L/mol K  Or 0.08206 L atm/mol K

Example: We can use this calculation to determine the gas constant. At STP 1 mol of gas will occupy 22.414 L. Find R. G V = 22.414 L n = 1.00 mol P = 101.325 kPa T = 0 °C = 273.15 K S = 8.314 kPa L / mol K R n = ? P Therefore the gas constant is 8.314 kPa L / mol K A PV = nRT

Example 2 : A liquid can be decomposed by electricity into two gases.   In one experiment, one of the gases was collected. The sample had a mass of 1.090 g, a volume of 850 mL, a pressure of 746 mm Hg, and a temperature of 25oC.  Calculate its molecular mass. 

Don’t copy In order to find the molecular mass we need the numbers of grams and the number of moles. The grams are given to us and the moles can be determined by using information given in the question.

G V = 850 mL = 0.850 L T = 25.0oC + 273.15 =  298.15 K R = 8.3143510  kPa L/mol K  S = 0.0341 mol R n = ? P Therefore the gas collected must be oxygen gas. A PV = nRT

Questions Page 445 #1-5, 7-9.