January 15 Agenda Do Now (10 mins) Pressure vs. Temperature (20 mins) Pressure Quick Demo (5 mins) Discuss Lab Tomorrow (15 mins) Exit Question (5 mins)

Do Now: Using the diagram below, in your group attempt to solve for the remaining two boxes in the # of molecules row on your Stoichiometry Activity. We will discuss these problems as a class. Moles given Moles unknown Mole-mole 3-step Conversion Molecules unknown Molecules known Divide by A’s Number Multiply by A’s Number

A gas is a substance that A gas is a substance that Uniformly fills a container Uniformly fills a container Mixes completely with other gases Mixes completely with other gases Is easily compressed Is easily compressed What is a gas?

The KINETIC MOLECULAR THEORY! 1. Gases consist of tiny particles (molecules or atoms) 1. Gases consist of tiny particles (molecules or atoms) 2. The particles are TINY compared to the space between them. Therefore, the volume of the individual particles is negligible (can be considered ZERO). 2. The particles are TINY compared to the space between them. Therefore, the volume of the individual particles is negligible (can be considered ZERO). Itty-bitty Itty-bity Space between = BIG

KMT continued 3. The particles are in constant RANDOM motion. The particles collide with the walls of the container. These collisions result in pressure. 3. The particles are in constant RANDOM motion. The particles collide with the walls of the container. These collisions result in pressure. Exerts pressure

Back to the KMT! 4. We assume the particles do not attract or repel each other. 5. The average kinetic energy (the energy of MOTION) of the particles is directly proportional to the temperature (the Kelvin temperature) of the gas. ?

A closer look at Temperature: 0 – A gas at 0 O C (such as O 2 ) might move like this: – A gas at 25 O C room temperature might move like this: 100 – A gas at 100 O C (the temperature at which water boils) might move like this:

Why the differences in speed? The higher the temperature the gas is at, the more Kinetic Energy (KE) the gas molecules have (the faster they move!) Kinetic Energy Temperature ?

So, to summarize, what variables, or factors, affect a gas? Pressure: the result of collisions of molecules on a surface Temperature: the average KINETIC energy of those molecules Volume: how much space the gas takes up Number of moles: how many molecules there are!

Let’s watch how these variables affect each other! ets/KineticMolecularTheory/PT.html ets/KineticMolecularTheory/PT.html ?viewkey=5ea31ccc387f

Talk about Tomorrow’s Lab

Exit Question When temperature increases, pressure ________. When temperature decreases, pressure ________.