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Gas Laws. By Sierra Dennison, Joshua Darling, Brittany Beckette. Characteristics of Gas. Evenly fill out whatever container it is in. It is compressed It has high energy and is excited It has a hotter temperature. Units of Pressure. 1 pascal= 1 N/m3 1 atm= 760 mmHg= 760 torr
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Gas Laws By Sierra Dennison, Joshua Darling, Brittany Beckette
Characteristics of Gas • Evenly fill out whatever container it is in. • It is compressed • It has high energy and is excited • It has a hotter temperature
Units of Pressure • 1 pascal= 1 N/m3 • 1 atm= 760 mmHg= 760 torr • 1 atm= 101.325 V= Volume P= Pressure T= Temperature Kelvin= C* +273.15
Boyles' Law • Pressure x Volume= Constant • P1 x V1=P2 x V2 • When the pressure doubles, the volumes goes by half. Example Problem: The pressure of a gas increases from 1.56 atm to 2.45atm. If the initial volume was 2.45 L, what would be its new volume? 1.56 atm x 2.45 L= 2.45 atm x V2 V2= 1.56 L
Charles' Law • Volume= Constant x Temp • V1/T1=V2/T2 • As the temperature increases, the volume increases. When heated, the gases expand and become more excited. • Temperature always in Kelvin Example: A gas is confined in an expandable contained i found to have a volume of 1.35 L and a temperature of 24.5*C. What will the volume be if it increases to 50.75*C? 24.5*C=297.65K 50.75*C= 323.90 K 1.35/297.65=V2/323.9 V2=1.47 L
Combined Law • Pressure x Volume/Temp = Constant • P1 x V1/T1 =P2 x V2/ T2 • Combination of Boyle's and Charles' Laws Example: A helium balloon with a volume of 3.00 L, a pressure of 100 kPa, and a temperature of 295K is put into an environment where the pressure is 50.0kPa and the temperature is 250K. What is the new volume of the balloon at this height? 3 x 100/295= V2 x 50/250 Fill in the info 75000=14750V2 Multiply each side V2=5.08 L Divide both sides to get answer
Ideal Gas Law • PV=nRT n=number of moles R=constant T= temperature P= Pressure .0821 atm, 8.315 kPa V= Volume
Ideal Example • Example: A gas exerts a pressure of 0.892 atm in a 5.00 L container at 15°C. The density of the gas is 1.22 g/L. What is the molecular mass of the gas? • PV = nRT T = 273 + 15 = 228 (0.892)(5.00) = n(.0821)(288) n = 0.189 mol .189 mol5.00L x x grams1 mol = 1.22 g/L x = Molecular Weight = 32.3 g/mol
Dalton's Law for Partial Pressure • P= n x RT/V • P(total)= P1 + P2 + P3 • A mixture of neon and argon gases exerts a total pressure of 2.39 atm. The partial pressure of the neon alone is 1.84 atm, what is the partial pressure of the argon? Ptotal = PNe + PAr 2.39atm=1.4 atm +PAr PAr =0.55atm
Kinetic Molecular Theory & Grahams Law • Kinetic molecular Theory- "Molecules are in continual straight line motion. The kinetic energy of the molecule is greater than the attractive force between them, thus they are much farther apart and move freely of each other. When the molecules collide with each other, or with the walls of a container, there is no loss of energy." • Grahams Law- the rate of effusion is inversely porportional to the square root of the mass of its particles • Rate1-rate of effusion for 1st gas • Rate 2- rate of effusion for 2nd gas • M1- molar mass for 1st gas • M2- molar mass for 2nd gas
Lesson Essential Questions • What are the characteristics of a gas? • What are the units of pressure? • How does pressure affect the volume of a gas? • How does temperature affect the volume of gas? • What two laws does the combined law contain?