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Bell work. If you have the titration and indicator labs, turn them in. If you were absent last class, it’s okay. We’ll talk about it shortly. 25 mL of 3.0 M NaOH reacts with 37.5 mL of HCl. What is the molarity of the HCl solution? How many grams of HCl are present in the solution?.
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Bell work • If you have the titration and indicator labs, turn them in. If you were absent last class, it’s okay. We’ll talk about it shortly. • 25 mL of 3.0 M NaOH reacts with 37.5 mL of HCl. What is the molarity of the HCl solution? How many grams of HCl are present in the solution?
Agenda • Bell work • Notes: Gas laws • Talk about final • Extra credit product • Look at grades • HW: Begin studying for final! Extra credit project!
Greek word-”kinetos” means “to move” Gases are made of tiny particles-atoms or molecules KMT-Kinetic Molecular TheoryGases SHAPE-Hard Spheres MOTION-Constant, independent, random WHY? Weak intermolecular forces yield lots of empty space between particles CHANGES IN MOTION-collisions, “rebound” off each other or the sides of a container COMPRESSIBLE-Lots of empty space
Collisions “rebound”=force/area=PRESSURE CollisionsPressure Collisions Pressure
How do we measure Pressure? 1 atm=normal atmospheric air pressure, simulator 1 Pascal = 1 Pa (The SI unit) 1 psi = 1 lb/in2 (English unit)-tires 1 mm Hg
If gases are invisible, how do we know they exist? Container Acts on something else (Force) Lungs inhale/exhale Smell fills a space what happens when you make the space larger
Factors that Affect Gas Pressure Amount in a Container-Too much-explodes Volume of Container Volume Pressure Volume Pressure Temperature Temperature Pressure
How do we measure Temperature? Kelvin: °C + 273 Examples: 20°C; -20°C T = 20°C + 273 = 293 K T = -20°C + 273 = 253 K For all gas calculations, make sure temperature is in Kelvin!
Combined Gas Law Formulas P1V1= P2V2 T1 T2 V1=initial volume V2= final volume P1=initial pressure P2 = final pressure T2=final temp T1=initial temp
The Combined Gas Law • How to use this law: Whenever you have a problem in which you change the pressure, volume, and/or temperature, just plug the values into it. • If one of the variables isn’t mentioned, we can assume that it’s kept constant and we can just cross it out of the equation.
Combined Gas Law-T is constant A balloon contains 30.0L of helium at 103 kPa. What is the volume of the helium when the balloon rises to an altitude where the pressure is only 25.0 kPa? 1)What do I know? 2) What am I solving for? 3) What is the equation?
Combined Gas Law-You Try Nitrous Oxide(N2O) is used as an anesthetic. The pressure of 2.50L of N2O changes from 15 atm to 3 atm. If the temperature does not change, what will the new volume be? 3) What is the equation? 1)What do I know? 2) What am I solving for?
Combined Gas Law-P is constant A balloon inflated in a room at 24°C has a volume of 4.00L The balloon is then heated to a temperature of 58°C. What is the new volume if the pressure remains constant? 1)What do I know? 2) What am I solving for? 3) What is the equation?
Combined Gas Law-P is constant-You Try Exactly 5.00L of air at -50°C is warmed to 100.0°C. What is the new volume if the pressure remains constant? 1)What do I know? 2) What am I solving for? 3) What is the equation?
Combined Gas Law Problem The volume of a gas-filled balloon is 30.0L at 311K and 153 kPa pressure. What would the volume be at STP (standard temperature(273K and pressure101.3 kPa)? 1)What do I know? 2) What am I solving for? 3) What is the equation?
Combined Gas Law Problem-You Try A gas at 155 kPa and 25°C has an initial volume of 1.00 L. The pressure of the gas increases to 605 kPa pressure as the temperature is raised to 125°C . What is the new volume? 1)What do I know? 2) What am I solving for? 3) What is the equation?
Ideal Gas Law More moles of a gas=more gas particles PV=nRT n= number of moles of gas R= .0821 L*atm mol*K 8.31L*kPa K*mol or
Ideal Gas Law Problem A child’s lungs can hold 2.2L. How many grams of air do her lungs hold at a pressure of 102 kPa and 37°C? The molar mass for air is 29 g/mol. 3) What is the equation? 1)What do I know? 2) What am I solving for?
Homework • Begin studying for final! • Start on extra credit project! • Due: • B day Thursday, May 26 • A day: Wednesday, May 25