Define MAC and what it means.
Minimum alveoli concentration necessary to prevent 50% of people from moving to a skin incision. MAC is the % of gas present in the atmosphere(lungs) at sea level (760mmHg)
How do you calculate partial pressure?
multiply sea level x % of gas
If you have 21% Oxygen, what is the pressure exerted by Oxygen in the atmosphere at sea level?
.21*760= 160mmHg
If you have 21% Oxygen, what is the pressure exerted by Oxygen in the atmosphere if you are in Denver. Assuming pressure there is 660mmHg.
0.21*660=139
What is standard temperature?
0 C or 273.15 K
What is pressure?
force exerted of a certain area
What is the standard unit of pressure?
Pascal (Pa)
What does Volume refer to?
volume occupied by a mass
Explain the Mole Concept.
1 mole= quantity of a substance containing same number of particles as there are atoms in 0.012kg of carbon12.
Molecular weight in grams= 1 mole of a substance
1 mole of any substance will contain 6.022x10^23 number of particles. (Avagadro's number)
Explain Avagadro's Hypothesis.
Equal volumes of gases at same temperature and pressure contain equal number of moles.
Re:Avagadro's Hypothesis at standard temp. (273K) and standard pressure (1atm) How much volume will be occupied by one mole?
v=nrt/p (1
0.08205
273)/1=22.4L
What is the number for the universal gas constant (r)?
0.08205
T or F Manipulating any variables of the universal gas law will cause changes in other variables.
True.
For example: Increasing the temp of an O2 cylinder without changing the volume will increase the pressure to the point it explodes.
Define Boyle's Law.
At a constant temperature the pressure and volume are inversely proportional to each other.
Explain Boyle's Law.
If the temp doesn't change and the pressure increases the volume decreases. The same is true if the volume increases the pressure decreases.
What is the mathematical expression for boyle's law?
PV=k or V=k(1/P) k is the constant it doesn't change so for this case the constant is temperature,#moles and gas constant.(PV=nRT)
If a gas normally occupies 5L at a pressure of 760mmHg. What would pressure be if volume of gas was increased to 8L?
P1V1/V2= 475mmHg
Define Charles' Law.
At a constant pressure, volume of a gas is directly proportional to absolute temperature.
Explain Charles' Law.
If pressure doesn't change and volume increases then the temperature increases. Same is true if volume decreases temperature decreases.
What is the mathematical expression of Charles' law?
V=kT or V/T=k k being the constant (in this case is pressure #moles and R) PV=nRT
A gas at a temp of 200K occupies a volume of 10L. Temp increases to 300K. What happens to the volume?
10/200=x/300 So, solve for x. 3000/200=15L
Define Gay Lussac's Law.
At a constant volume, pressure of a gas is directly proportional to absolute temperature.
Explain Gay Lussac's Law.
If volume doesn't change and pressure increases the temp will increase. Same is true if pressure decreases the temp will decrease.
What is the mathematical expression of Gay Lussac's Law?
k=P/T or Pk=T k is the constant (in this case is volume, #moles, R) PV=nRT
Explain Adiabatic Changes in Gas.
In this process no heat is added or removed from a system. Generally occurs when a gas expands so rapidly that there is no time for heat exchange.
What effect explains adiabatic changes in gas? Describe this effect.
Joule-Thomson Effect "Joule is Cool" Gas comes out at high pressure and cools as it expands rapidly at atmospheric pressure.
Define Universal Gas Law.
behavior of liquids, gases, and vapors depending on specific variables: PV=nRT; pressure, volume, number of moles in a substance, universal gas constant, and temperature.
Explain condenstation.
By manipulating more than one variable, you can create a liquid faster. Condensation is when a gas becomes a liquid. This occurs when pressure is increased and temperature decreases.
Explain Dalton's Law of Partial Pressure.
When there is a mixture of gases in a container: Pressure in container is related to frequency of collisions, mass, and velocity of molecules. Pressure exerted by each gas is same as if it occupied the container alone. Each gas acts independently of each
What is the partial pressure of 21% oxygen ina cylinder of air at ambient pressure (100kPa)? Then take it a step further when inhaling that air, by the time it reaches alveoli it has become humidified with H2O vapor.(alveoli+H2O=6.18%) So, what is the PAO
Convert kPa to mmHg (100kPa=1atm=760mmHg). Then mulitply .21 by 760=160mmHg
Now you multiply 6.18% by 760=47mmHg. Then you subtract initial pressure from final pressure 760-47=713 Then you do 21% of that and you get 149mmHg for the PAO2.
Define Critical Temperature.
Temperature above which a gas can not be liquefied, regardless of pressure.
You can apply as much pressure as you want but it will never go into a liquid. Above critical temp attractive forces between molecules are never sufficient enough to overcome thei
When can a gas be liquefied?
When it is at critical temp or below.
Define critical pressure.
Pressure necessary to liquefy a gas at its critical temperature.
Is the storage of O2 in O2 tank knowing that its critical temp is
-118.4C a liquid, gas, or a mix of both?
If you put this gas at room temp which is 20C the temp raises above critical temp therefore it is a gas.
What is the difference between a vapor and a gas?
Vapor is a substance in a gaseous state but below its critical temperature. A gas is above critical temperature.
Air with a critical temp of -140.3C is it a gas or a vapor?
Gas
If a vapor is in its gaseous state how is it stored at room temperature?
as a liquid because it's critical temp is above room temp.
Would you expect volatile agents to have a very high or low critical temp?
High because at room temperature they are stored as liquids therefore their critical temp has to be above room temp.
Define equilibrium.
Condition of a system in which resultant of all acting forces is zero.
Explain point of equilibrium.
when the rate of forward reaction is equal to rate of backward reaction. A stable pressure exists, there are = # of molecules going into solution as there are moving into a gaseous state. Because both reactions are still occuring this is known as dynamic
Define Le Chatelier's Principle.
any change in a system at equilibrium results in a shift of equilibrium in direction which minimizes change. "dynamic equilibrium concept
Does equilibrium mean concentration of gas in both areas is the same?
No
Define vapor pressure.
Looking at a gas in combo of vapor and liquid state at equilibrium it is the pressure exerted by the vapor.
Explain when you would have high vapor pressures and low vapor pressures.
liquids with high intermolecular attractive forces will have low vapor pressure.
liquids with low intermolecular attractive forces will have high vapor pressure.
T or F Different liquids have different vapor pressures at same temperature and volume.
True
Define boiling point.
temp at which vaporization begins to take place throughout body of liquid.
What has to occur before boiling point can occur?
vapor pressure of the liquid must be at or just above atmospheric pressure
Does boiling point change with atmospheric pressures?
yes
Characteristics of vapors are such that vapor pressures depend on what?
solubility of the substance
Define solubility.
A measure of ability of solute to dissolve in a particular solvent.
What are the variables of solubility?
MW/size, intermolecular forces b/w solute and solvent, temp, pressure, concentration
What is Henry's Law?
law that relates to solubility stating that quantity of gas that will dissolve in a given amount of liquid at a constant temperature is directly proportional to partial pressure of gas
What is the formula of Henry's Law?
pressure=concentration of dissolved gas/solubility coefficient value
If pressure is applied to a cylinder do you get more gas or more dissolved products due to the increase in pressure?
more dissolved products
Define coefficient
in physics it is the quantity constant for a given substance, body, or process under certain specified conditions that serve as a measure of some of its properties
Define solubility coefficient.
Numerical derived values used to express volume of gas (solute) that will dissolve in a given volume of liquid (solvent) per given pressure.
What are the names for the solubility coefficient and the coefficient?
Otswald solubility coefficent
Bunsen coefficient
What does the solubility coefficent represent?
a ratio of concentrations (moles/liters) per pressure of gas in dissolved and gaseous states
Explain what occurs when the concentration of a gas dissolved in a liquid vs gaseous state when at equilibrium.
There is no difference in partial pressure. The gas is still a gas, just dissolved in a liquid. This doesn't mean its liquefied.
Partial pressure of gas in vapor state is equal to that in the liquid state-no gradient exists to push in either direction.
Explain what would occur if you had the same gas at different equilibrium states depending on other variables. ie: if you increase temp what occurs? decrease temp what occurs?
with increased temp more gas will be in gas phase.
with decreased temp more gas will be dissolved.
Define Otswald Solubility Coefficient.
volume of gas that dissolves in a unit of volume of liquid at temperature concerned
Explain what occurs if you have a gas/blood concentration that is higher than others.
It is more soluable. Therefore less is going to get to brain, because pressure in the alveoli is low so more gas is going into the blood.
Explain what occurs if you have a gas/blood concentration that is lower than others.
It is less soluable. Therefore more is getting to the brain, because the pressure in the alveoli is high.
What is the difference in Bunsen and Otswald coeffecients?
They are the same except Bunsen uses standard temp (0C or 273K) and standard pressure (760mmHg)
Define partition coefficients.
Distribution of a substance between 2 phases or ratio of concentration of a gas dissolved in each volume of 2 different phases (ex/ solid/liquid) when equilibrium is established between both phases and gaseous state.
What is partition coefficient similar to?
Solubility coefficient
What does it mean if you have a low partition coefficent?
the gas wants to be in a gaseous state more than a dissolved state.
What is the significance of solubility and partition coefficents?
To know the pharmacokinetics of anesthetic gases. It helps knowing induction and emergence times. How to treat light and deep anesthesia
Define diffusion.
transfer of a substance from one location to another by a process of molecular intermingling.
How does movement occur in diffusion?
High concentrations to low concentrations
What accelerates intermingling in diffusion?
heat, mechanical agitation, hydrostatic pressure differences, or an electrical field
What is Fick's Law of Diffusion?
Rate of diffusion= KA(P1-P2)/D
K= diffusion constant of a drug
A=Area
P1-P2= Pressure gradient of gas
D= thickness of membrane
Clinical app of Ficks Law: When using N2O over time, what happens to the balloon of the ETT? Why?
It expands, because the pressure gradient for N2O encourages diffusion into the cuff, and N2 out of the cuff. N2O is more soluble than N2 so more N2O is diffusing into the cuff than N2 is diffusing out.
According to Poiseuille's Law what has the biggest factor on fluid flow?
Radius
Define Graham's Law.
diffusion flow of gases, both through membranes and in solutions, is inversely proportional to square root of molecular weight of gas (assuming gradient is kept constant)
Explain what Graham's Law means.
The larger the molecule, the slower it diffuses.
Which law applies in regards to administering colloids instead of crystalloids?
Graham's Law