Chapter 6, Gases
Average Air pressure at sea level with every Unit
This also functions as a coversion between pressure unit because they equal each other 1.) Atmospheres (atm) = 1 atm 2.) Pascals = 101,325 Pa 3.) Pounds per square inch = 14.7 psi 4.) Torr = 760 torr 5.) inches of mercury = 29.92 in Hg
Avogadro's Law
This law relates volume and moles aka the amount of gas particles under CONSTANT temperature AND pressure - Volume is DIRECTLY proportional, V1/n1 = V2/n2 - n = number of moles
Molar Volume
Volume occupied by 1 mole at STP = 22.4 L/mol
Charle's Law
Volume of a gas is directly proportional to it's temperature Under constant pressure V1/T1 = V2/T2 - Increasing volume of gas will increase the temperature of the gas ONLY IF pressure remains the same
Standard Conditions (STP)
When the volume of mole of a gas which is known as and has value of: - Standard Temperature = 273 K = 1 C - Standard Pressure = 1 atm
Kinetic Molecular Theory
a model that assumes that an ideal gas is composed of tiny particles (molecules) in constant motion
Mole Fraction
number of moles of desired gas divided by the total number of moles in the mixture
Root Mean Square speed of molecules
speed of particles in a gas - R = gas constant (in 8.314 [(Kg)(m^2)s^-1)(mole^-1)]) - T = Temperature (in Kelvin) - M = Molar mass of the gas (in Kg/mol)
Diffusion
when particles that are packed together spread out - High concentration ---> Low concentration
How do you solve Molar Volume at STP
1.) use ideal gas law PV = nRT 2.) arrange to solve Volume 3.) Note that T = 273 K & P = 1 atm 4.)
Boyles Law
A principle that describes the INVERSE relationship between the pressure and volume gas at constant temperature At constant temperature and moles of gas: - P1V1 = P1V2 - where P is pressure and V is volume
Effusion
A process by which gas particles pass through a tiny opening
Barometer
Ecuated glass tube, the tip of which is submerged in a pool of mercury
Van der Waal's Equation
Equation made to account for molecular volume and intermolecular forces - a = vander der waal's constant - b = another Waal's constant - these constants are different for each gas
Celsius to Fahrenheit conversion
F = (C x 9/5) + 32
Pressure
Force exerted per unit area - P = F/A - SI Unit = N/m^2 = Pa = Pascal
Vapor Pressure
The partial Pressure of water vapor
What happens when particles collide in kinetic molecular theory?
The particles exchange energy but there is no loss in energy
Partial Pressure
The pressure of a single gas in a mixture of gases
Dalton's Law of Partial Pressures
The total pressure of a gas mixture is the sum of the partial pressures of its individual gases. P_total = (P_a) + (P_b) + (P_c) + ...
Average Kinetic Energy
The Kinetic energy of gas molecules depends on the average mass and velocity. KE = 1/2(N_A)(m)(u)^ - KE = Average Kinetic energy - N_A = Avogadros number (6.022*10^23) - m = mass - u = velocity
Gas Constant (R) value
R = 0.08206 (L*atm)/(Mol*K) - "Liter-atmospheres per Moles-Kelvin"
What are the conditions for a gas to behave ideally
- High Temperature - Low Pressure
Pressure and concentration relationship
- Increasing concentration INCREASES Pressure - increasing Volume (decreasing concentration) DECREASES Pressure
Charle's Law Real life examples
- One reason a helium balloon decends after some time. it cools down which decreases the volume slightly making it denser, but the main reason is helium molecules escaping - Same thing for a hot air balloon expect instead you are heat the air which causes the volume to expand.
Variables used in the ideal gas law
- P = Pressure - V = Volume - n = Number of Moles present (amount) - R = Gas constant - T = Temperature
Partial pressure from Mole fraction
- P_a = Partial pressure of gas in mixture - X_a = Mole fraction of gas in mixture - P_total = total pressure in the mixture
Units of Pressure
- Pascal = Pa = N/m^2 - Pounds per sqaure inch (psi) = lb/in^2 - Torr - Inches of mercury - atomospheres
Graham's Law of Effusion
- Rate 1 & 2 = How fast gases 1 & 2 escapes through tiny hole - M = Molar masses
The Simple Gas Laws
1.) Boyle's Law 2.) Charles's Law 3.) Avogadro's Law 4.) Ideal Gas Law
Three Postulates of Kinetic Molecular Theory
1.) Gas molecules are negligibly small 2.) Average kinetic energy of particle is proportional to temperature in Kelvin 3.) collision of one particle with another (or walls of container) is completely elastic
Boyles Law and diving in water
If you are deep underwater and you rise quickly the air in your lungs will expand due to the pressure increase therefore: - EXHALE when rise from high pressure
Celsius to Kelvin Conversion
K = C + 273
Ideal Gas Law
Law that combines the other three laws together, contains: - Boyle's Law - Charle's Law - Avogadros Law Pv = nRT The conditions of the other gas laws are solved by setting 2 the necessary variable(s) constant
Mean Free Path
average distance particles travel between collisions
Density of a Gas at STP
d = [molar mass]/[molar volume]
