Objective: To introduce the properties of gases and its factors Do Now: What are some of the properties of a gas?

Kinetic Theory of Gases Particles of gases are to be small, hard spheres with insignificant volume Motion of gases is rapid, constant and random All collisions between particles are perfectly elastic

Gases Indefinite shape and volume Compressibility- measure how much of the volume of matter decreased under pressure This plays a significant role in airbags

Gases Gases are easily compressed because of the spaces between the particles With increase of pressure, the gas particles are forced closer together

Three Factors that effect gas pressure Gas pressure: results from force exerted by gas per unit surface area of an object – This results in billions of rapidly moving particles in a gas simultaneously colliding with an object Amount of gas particles, volume and temperature effects these gas pressures

Atmospheric Pressure Barometer- instrument used to measure atmospheric pressure SI unit for pressure- pascal (Pa) Two other pressure units are still commonly used today: millimeters of mercury (mm Hg) and atmosphere (atm)

Atmosphere pressure conversions 1 atm = 760 mm Hg = kPa Sample problem: What pressure, in both kilopascal and in atmospheres, does a gas exert at 385 mm Hg?

385 mm Hg= x kPa 760 mm Hg101.3 kPa X = kPa 385 mm Hg=x atm 760 mm Hg1 atm X = 0.51 atm

Kinetic Energy v Temperature Kinetic Energy: moving energy (particles are in motion) Temperature and kinetic energy are directly proportional to one another – As temperature increases, so does kinetic energy – As temperature decreases, so does kinetic energy

Objective: To know and calculate the four gas laws Do Now: What is the pressure, in both kilopascals and atm, of 625 mm Hg?

Three gas laws Boyle’s Law Charles Law Gay—Lussac’s Law

Boyle’s Law Pressure and volume are inversely proportional IF you squeeze a balloon, the volume decreases but the pressure increases P 1 V 1 = P 2 V 2

Boyle’s Law Balloon contains 30L of helium gas at kPa. What is the volume of helium when the balloon rises to an altitude where the pressure is only 25.0 kPa Note what you are given P1= kPa V1= 30L

Balloon contains 30L of helium gas at kPa. What is the volume of helium when the balloon rises to an altitude where the pressure is only 25.0 kPa Now you need to find your unknown and new pressure or volume P2 = 25.0 kPa V2 = x (103.5)(30)= (25)(x)x = L

Charles Law Volume and temperature are directly proportional – Temperature decreases, so does volume – Temperature increases, so does volume Hot air balloons

Charles’s Law V 1 = V 2 be sure Temperature is converted to kelvin (273.15) T 1 T 2 A balloon inflated at a room in 24 degrees Celsius has a volume of 4.00L. The balloon is then heated to a temperature of 58 degrees Celsius. What is the new volume of the balloon?

First find your initials T1 = 24 degrees Celsius = K V1 = 4.00L Next find your unknown and second temp or volume T2 = 58 degrees Celsius = K V2 = x

(4)= x X = 4.46 L

Gay-Lussac’s Law Temperature and Pressure is directly proportional – Temperature decreases, so does pressure – Temperature increases, so does pressure Tires of a car

Gay-Lussac’s Law P 1 =P 2(be sure Temperature is in Kelvin (273.15)) T 1 T 2 The gas in a used aerosol can is at a pressure of kPa at 25 degrees Celsius. If the can is thrown to a fire, what will the pressure be when the temperature is at 928 degrees Celsius?

First, figure out your initial temperature and pressure T1 = 25 degrees Celsius = = K P1 = kPa

The gas in a used aerosol can is at a pressure of kPa at 25 degrees Celsius. If the can is thrown to a fire, what will the pressure be when the temperature is at 928 degrees Celsius? Next find your unknown and new temperature or pressure T2 = 928 degrees Celsius = K P2 = x Now set up equation

101.3 = x X = kPa

Objective: To know and calculate the four gas laws Do Now: Match the Gas Law to its equation 1. Boyle’s Law 2. Charles’s Law 3. Gay-Lussac’s Law A. (P 1 /T 1 )= (P 2 =T 2 ) B. P 1 V 1 = P 2 V 2 C. (V 1 /T 1 ) = (V 2 /T 2 )

Ideal Gas Aside from temperature, volume and pressure, amount of moles of a gas needs to be considered Ideal gas relates to how gases ideally are calculated and how they behave

Ideal Gas Law PV = nRT R= 8.31 (kPa x L) /(K x mol) If pressure, volume, and temperature is known, you can find the moles of a gas R is a constant, so it does not change (be sure your units are in Kelvin, kilopascal, moles, and liters)

Try this out (PV=nRT) At 34 degrees Celsius, the pressure inside a nitrogen-filled tennis ball with a volume of 0.148L is 212 kPa. How many moles of nitrogen gas are in the tennis ball? T= = K V= 0.148L P= 212 kPa R= 8.31 (kPa x L)/(K x mol) n= x

PV=nRT 212 x = n x 8.31 x = n x n = moles

Ideal Gas versus Real Gases Ideal Used for kinetic theory assumptions No volume Elastic attraction Under certain conditions, you are able to calculate number of gas particles Real Have volume Has attraction when collide Explains condensations Differ most with ideal in low temperature and high pressure