Kinetic Molecular Theory Lesson PDF

Kinetic Molecular Theory (KMT) SCH3U - Gas Chemistry Previously On… Matter ▪ What are the three states of matter? ▪ How do we change between states of matter? Previously On… Matter ▪ Changes in state occur when energy is added to a given substance H2O (s) energy H2O (l) energ...

Kinetic Molecular Theory (KMT) SCH3U - Gas Chemistry Previously On… Matter ▪ What are the three states of matter? ▪ How do we change between states of matter? Previously On… Matter ▪ Changes in state occur when energy is added to a given substance H2O (s) energy H2O (l) energy H2O (g) ▪ More energy increases the motion (or kinetic energy for the physics nerds) of the particles Previously On… Matter Remember: heat is energy! If heat is absorbed, energy is absorbed by the system. If heat is released, energy is being released by the system. Previously On… Matter ▪ How would you rank the following in terms of their boiling point? H 2O CCl4 MgBr2 Previously On… Matter ▪ Recall the particle theory of matter where the attractions between particles influence the state of each substance ▪ Ionic: strong attractions - solid at room temperature, high boiling points ▪ Polar: permanent dipoles forming strong dipole-dipole intermolecular bonds - liquid or solid at room temperature, but lower boiling points (attractive forces are strong, but not as strong as ionics) (ie. H2O(l)) ▪ Nonpolar: no dipoles, weak intermolecular bonds - gases (ie. H2 (g), CO2 (g) )  I can describe the Learning Goals I can identify the properties of different types of particles as they particle motion transition through phases I can describe the I can convert properties of ideal temperature, and real gases pressure and using Kinetic volume into Molecular Theory different units Particle Motion Types of Molecular Motion 1. Vibrational Motion: particles move or vibrate back and forth Types of Molecular Motion 1. 2. Rotational Motion: particles rotate and change orientation/position about the x and y axes Types of Molecular Motion 3. Translational Motion: particles move from place to place Heating Curve of Water State or What is happening? Change Increasing vibrational motion A solid (kinetic energy) Intermolecular bonds are B melting weakened Increasing vibration and C liquid rotational motion D boiling Intermolecular bonds are broken Increasing vibrational, rotational E gas and translational motion Heating Curve of Water Q: Why are there flat portions of the curve? A: This is where a change in state happens. Temperature does not change (at boil or melt point), but energy is still required to weaken or break all intermolecular forces so that every particle transitions to a new state of matter.  Comparing the States of Matter Properties Solid Liquid Gas Volume fixed Shape fixed Attractive Forces strong Space Between Particles low Compressibility incompressible Motion of Particles vibrational Degree of Disorder (Randomness) low  Comparing the States of Matter Properties Solid Liquid Gas Volume fixed fixed very variable Shape fixed variable variable Attractive Forces strong weaker very weak Space Between Particles low low high Compressibility incompressible incompressible very compressible vibrational vibrational Motion of Particles vibrational rotational rotational translational Degree of Disorder (Randomness) low moderate very high The Kinetic Molecular Theory of Gases  The Kinetic Molecular Theory of Gases ▪ The main idea of the kinetic molecular theory (KMT) is that the entities in solids, liquids, and gases are in constant, random motion. As they move, they collide with one another and objects in their path ▪ Remember: Kinetic energy is the energy of an entity due to its motion.  The Kinetic Molecular Theory of Gases ▪ The KMT states… 1. Individual gas particles have no volume (negligible) compared to the space between the particles. 2. No attractive or repulsive forces between the particles in a gas.  The Kinetic Molecular Theory of Gases 3. Gas particles move randomly in a straight line (high translational KE). 4. When gas particles collide, the collision is elastic, meaning no loss of kinetic energy.  The Kinetic Molecular Theory of Gases 5. The average kinetic energy of a gas is directly related to temperature. The greater the temperature, the _______________ the kinetic energy.  Real vs. Ideal Gases ▪ Ideal Gases: describes a hypothetical gas, follow the KMT of gases (e.g. have no volume, collisions are elastic, no interactions between particles) ▪ Real Gases: have predictable properties under normal temperature and pressure conditions, but do not always follow KMT under all temperatures and pressures (e.g. they have volume, energy lost in collisions, intermolecular forces) ▪ Only at high temperatures and low pressures will real gases behave like ideal gases Real vs. Ideal Gases Temperature, Pressure & Volume in Chemistry Pressure ▪ Pressure: a measure of force per unit of area ▪ When gas particles strike the walls of their container, they exert a force ▪ The metric unit of measure for pressure is the Pascal (Pa) this is a kilopascal, you may need to convert from Pa to kPa or vice versa Atmospheric Pressure ▪ The pressure of our atmosphere, also known as barometric pressure (because it is measured with a barometer) 760 mm Hg = 760 torr = 1.00 atm = 101.3 kPa ▪ Since all of these measurements are equivalent, we can use them as conversion factors: These conversion factors are on the back of your periodic table! Atmospheric Pressure ▪ The pressure of our atmosphere, also known as barometric pressure (because it is measured with a barometer) 760 mm Hg = 760 torr = 1.00 atm = 101.3 kPa ▪ Since all of these measurements are equivalent, we can use them as conversion factors: These conversion factors are on the back of your periodic table! Temperature ▪ Temperature: measure of the average Celsius (oC) Kelvin (K) kinetic energy possessed by the particles of a substance 100 ? ▪ We don’t always use room temperature to conduct reactions (extreme heat or cold), so 25 ? celsius is not always the best measurement 0 273.15 ▪ Absolute Zero: temperature at which all particle motions stops, 0 K / -273.15oC ▪ To convert between Kelvin and Celsius: TK = TC + 273.15 TC = TK - 273.15 -273.15 0 Temperature ▪ Temperature: measure of the average Celsius (oC) Kelvin (K) kinetic energy possessed by the particles of a substance 100 373.15 ▪ We don’t always use room temperature to conduct reactions (extreme heat or cold), so 25 298.15 celsius is not always the best measurement 0 273.15 ▪ Absolute Zero: temperature at which all particle motions stops, 0 K / -273.15oC ▪ To convert between Kelvin and Celsius: TK = TC + 273.15 TC = TK - 273.15 -273.15 0 Volume ▪ Units: 1 mL = 1 cm3 1 L = 1000 mL = 1000 cm3 ▪ Complete the following: ▪ 25 cm3 = _____ mL ▪ 182 cm3 = _____ L Metric conversion factors are on the back of your periodic table! Volume ▪ Units: 1 mL = 1 cm3 1 L = 1000 mL = 1000 cm3 ▪ Complete the following: ▪ 25 cm3 = 25 mL ▪ 182 cm3 = 0.182 L Metric conversion factors are on the back of your periodic table! Standards in Chemistry ▪ Standard Temperature & Pressure (STP) Often times you’ll get a chemical ▪ Temperature = 0oC / 273 K reaction where it must be ▪ Pressure = 101.3 kPa (old) or 100 kPa performed “at STP/SATP”. These conditions are easy for chemists to reproduce in a lab as reactions will occur differently ▪ Standard Ambient Temperature & (e.g. time to complete reaction) Pressure (SATP) under different temperatures ▪ Temperature = 25oC / 298 K and pressures. These are also on ▪ Pressure = 101.3 kPa (old) or 100 kPa the back of your periodic table!  Work Time! Complete worksheet questions posted on Brightspace Questions cover KMT as well as the conversion of P/T/V units