Chapter 5 Flashcards
what is pressure?
a measure of force exerted per unit area; in chemistry, most commonly the force exerted by gas molecules as they strike the surface around them
P= F/A ( pressure can be measured in several different units)
what is the unit millimeter of mercury (mmHg) aka Torr?
a common unit of pressure referring to the air required to push a column of mercury to a height of 1mm in a barometer (760 mmHg = 1 atm = 101.325 kPa)
aka the Torr named after the Italian physicist Evangelista Torricelli
what is a barometer?
an instrument used to measure atmospheric pressure
what is the a Pascal?
The SI unit of pressure defined as 1 N/m^2
what is an atmosphere?
a unit of pressure based on the average pressure of air at sea level; 1 atm = 101 325 Pa)
101 325 Pa = 101.325 kPa = 760 Torr = 1 atm
what is standard pressure?
100 000 Pa or 1 bar
what is the bar?
a unit of standard pressure that is equal to 100 000Pa
what is a manometer?
an instrument used to determine the pressure of a gaseous sample, consisting of a liquid-filled U-shaped tube with one end exposed and the other connected to the sample
(height difference (h) indicates pressure of gas relative to atmospheric pressure)
what is Boyle’s Law?
The law that states that the volume of a gas is inversely proportional to its pressure
P1V1 = P2V2
what is Charles law?
The law that states that temperature is directly proportional to to its temperature
V1/T1 = V2/T2
what is Avogadro’s Law?
The law that states that the volume of a gas is directly proportional to its amount in moles
V1/n1 = V2/n2
what is the Ideal Gas Law?
The law that combines the relationships of Boyle’s Law, Charles Law, and Avogadro’s Law into one comprehensive equation of state with the proportionality constant R in the form PV = nRT
what is an ideal gas?
a gas that perfectly follows the ideal gas law
what is the ideal gas constant?
The proportionality constant of the ideal gas law R, equal to 8.314 J/molK or 0.08314 bar L/molK
what is molar volume?
the volume occupied by one mole of a substance
often specified under the conditions known as STP (Standard Temperature and Pressure)
what is STP?
The conditions when T = 273.15K and P = 1bar and V = 22.4L
Density of a gas?
since we know the molar volume of an Ideal gas under STP, we can readily calculate the density if a gas under these conditions PV = nRT ; n=m/M PV = (m/M)RT; d=m/V m/V = PM/RT d = PM/RT
molar mass of a gas?
we can use the ideal gas law in combination with mass measurements to calculate the molar mass of an unknown gas
PV = nRT; n = m/M
PV = (m/M)RT
M = mRT/PV
what is partial pressure?
the pressure due to any individual component in a gas mixture
What is Dalton’s Law of Partial Pressures?
The law stating that the sum of the partial pressures of the component gas mixture must equal the total pressure
Ptotal = P(a) + P(b) + ….
P(a)=n(a)RT/Vtotal + P(b) = n(b)RT/Vtotal …= n(total) = RT/Vtotal
what is a mole fraction?
The number of moles of a component in a mixture divided by the total number of moles in the mixture
X(a) = n(a)/n(total)
P(a) = X(a)P(total)
what is hypoxia?
A physiological condition caused by low levels of oxygen, marked by dizziness, headache, and shortness of breath and eventually unconsciousness or even death in severe cases
what is oxygen toxicity?
a physiological condition caused by an increased level of oxygen in the blood, resulting in muscle twitching, tunnel vision and convulsions
what is nitrogen narcosis?
a physiological condition caused by an increased partial pressure or nitrogen, resulting in symptoms similar to those of intoxication
what is Vapour pressure?
the partial pressure of a vapour in dynamic equilibrium with its liquid
Collecting gas over water?
P(total) = P(diatomic gas) + P(H2O)
What is the Kinetic Molecular Theory?
Average kinetic energy proportional to volume of particle
1. The size of a particle is negligibly small.
2.The average kinetic energy of a particle is proportional to the temperature (in K).
3.Completely elastic collisions between particles
THEORY ASSUMES ALL COLLISIONS ARE ELASTIC, THIS IS NOT A REAL LIFE SCENARIO
How does KMT relate to Boyle’s Law
as Volume increases, Collisions decrease, and Pressure decreases
How does KMT relate to Charles Law?
as Temperature increases, Collisions increase, and pressure increases
How does KMT relate to Avogadro’s Law?
as Moles increase, Collisions increase, and Pressure increases
How does KMT relate to Dalton’s Law?
as Moles increases, Collisions increases, and Pressure increases
Kinetic Molecular Theory and Ideal Gas Law?
P = F(total)/A(area)
F(collision) = m(velocity/t) = m(2velocity/t)
#of collisions = (velocitytA)(n/V)
P = (m*velocity^2)(n/V)
Temperature and its relation to Molecular velocities
- speed will depend on the weight of a particle
- particles of different mass will have the same kinetic energy at a given temperature Ek = 0.5mv^2
-In a gas at a given temperature, lighter particles travel faster (on average) than heavier ones
u(rms) = √u^2 = √3RT/M
what is u(rms)
is the speed of a particle, represents an average of all speeds
what does mean free path mean?
The average distance a molecule in a gas travels between collisions
what is diffusion?
The process by which a gas spreads through a space occupied by another gas
what is effusion?
The process by which a gas escapes from a container into a vacuum through a small hole
Rate of effusion = 1/√M
Rate of effusionS = ΔV/Δt
what is Graham’s law of effusions?
the expression of the ratio of of rates of effusion of two different gases
Rate(a)/Rate(b) = Rate of effusionS = √M(a)/M(b)
What is Van der Waals equation?
The extrapolation of the ideal gas law that considers the effects of intermolecular forces and particle volume in a non-ideal(real gas)
P + a(n/V)^2 * (V - nb) = nRT
what is the real gas formula compared to the ideal gas formula?
Ideal Gas = V = nRT/P
Real Gas = V = nRT/P + nb(bar)
V(ideal) = V(real) - nb
what is the correction in the real gas formula from the ideal gas formula for particle volume?
nb
what is the correction in the Van der Waals formula from the ideal gas formula for intermolecular forces?
(n/V)^2
