Topic 1 – Stoichiometric Relations

Topic 1 – Stoichiometric Relationships 1.3 – Reacting masses and volumes SWBAT: Solve problems and analyze graphs involving the relationship between temperature, volume, and pressure for a fixed mass of gas Solve problems using the Ideal Gas law Explain deviation of real gas behavior from at low temp and high pressure Obtain experimental values to calculate the molar mass of a gas from the ideal gas law Solve problems involving concentration, amount of solute, and volume of solution Use a titration to calculate the concentration of a solution by reference to a standard solution

Gas Laws Boyle’s Law (inverse relationship) P 1 V 1 =P 2 V 2 Charles’ Law (direct relationship) V 1 /T 1 = V 2 /T 2 Combined Gas Law P 1 V 1 /T 1 = P 2 V 2 /T 2 Ideal Gas Law PV=nRT when pressure is in atm R= when pressure is in kPa R=8.314

Real gases show deviation from ideal behavior What 2 conclusions can you come up with regarding how the gas behaves most like an ideal gas? (ie under what conditions)

Real gases show deviation from ideal behavior 1)The gas behaves most like an ideal gas at low pressure and shows its greatest deviation at high pressure 2)The gas behaves most like an ideal gas at high temperature and shows the greatest deviation at low temperature

Real gases show deviation from ideal behavior To interpret these findings we will question the validity of 2 assumptions made in describing an ideal gas in the kinetic molecular theory: 1)The volume of the gas particles are negligible 2)There are no attractive forces between the particles

Real gases show deviation from ideal behavior 1)The volume of the gas particles are negligible At low pressures the volume occupied by the particles of a typical gas is only ~0.05% of the total volume, so its reasonable to describe this as negligible With increasing pressure as the space b/w the particles is reduced, this percentage increases up to ~20% - certainly not negligible

Real gases show deviation from ideal behavior 2)There are no attractive forces between the particles When a gas is at low pressure the particles are so far apart they aren’t attracted to each other As pressure increases & the particles move closer together the attractive forces b/w them strengthen

Concentration Molarity=mol solute / L solution

Name that glassware!

Concentration Molarity=mol solute / L solution

Concentration parts per million (ppm)= mass of component/total mass of solution * 10 6

Dilutions of solutions reduce the concentration As a solution is diluted the # of moles of solute remains the same, but they become spread through a larger volume, decreasing the concentration M 1 V 1 =M 2 V 2 where M=molarity and V=volume CoCl 2

Dilutions of solutions reduce the concentration