Gas Laws Part B Flashcards
Do ideal gases exist?
No ideal gases do not exist
The kinetic theory of gases says what?
Assumes that the molecules are very small relative to the distance between molecules. The molecules are in constant, random motion and frequently collide with each other and with the walls of any container.
What value does the average kinetic energy depepon on?
Temperature
Define pressure of a gas:
A measure of the linear momentum of the molecules as collisions against the walls of a container occur
What does Force/Area equal?
Pressure
Define temperature of a gas:
The mean kinetic energy of the gas.
Define density of a gas:
The sum of the mass of the molecules divided by the volume which the gas occupies
The sum of the kinetic energy and potential energy is what?
Internal energy
Does temperature increase add or substract from the average KE of the molecules in a gas?
It is added energy and increases the average KE
Define diffusion:
The movement of a substance from an area of higher concentration to an area of lower concentration.
Define effusion:
The movement of a gas through a small opening.
How does Graham’s Law of Effusion relate to anesthesia?
The basis for how anesthetic gas/preoxygenation works. No matter what, a concentration gradient must be present for movement.
As molecular weight increases, what happens to effusion/diffusion rates?
Decrease.
The rate of effusion is inversely proportional to the square root of the molecular weight.
How does the molecular weight and effusion rate apply clinically?
Helium moves much faster and easier through a small airway than air/oxygen
Fick’s Law determined there are four factors that effect diffusion of a gas across a permeable membrane. What are they?
- Chemical nature of membrane.
- Surface area of membrane.
- PP gradient.
- Thickness of the membrane
With what patients would you never use N2O?
Pneumothorax, inner-ear surgery, intra-abdominal, eye surgeries.
What is the process by which the fetus receives O2 ?
Simple diffusion across a membrane.
What is Henry’s Law?
The amount of non reacting gas which dissolves in liquid is directly proportional to the partial pressure of the gas, provided the temperature remains constant.
How much O2 gets dissolved in blood?
0.003ml/100ml blood
How do you calculate amount of dissolved O2 or CO2?
Multiply pp of O2 by 0.003.
Multiply pp of CO2 by 0.067
Will a cold patient require more or less anesthetic? Longer or shorter to wake up?
Colder patient will requires less gas and will take longer to wake up.
What is Ostwald’s Solubility Coefficient?
The higher the coefficient the more readily the gas dissolves in liquid.
What does it mean if the Ostwalds Solubility Coefficient (blood/gas partition coefficient) is 1.8
Means that at equilibrium, the concentration in blood will be 1.8 times higher than the concentration in the alveoli.
As the blood/gas coefficient increases, what happens to anesthetic gas requirement?
High blood/gas coefficient means slower induction.
How does the Meyer Overton rule relate to anesthetics gases?
Agents will increased oil solubility have greater potency.
Ideal gases obey all gas laws; however, real gases deviate with what values?
High pressure and/or low temperature
What does Van der Waals Equation correct for?
Corrects for intermolecular attraction between gaseous molecules and for the finite volume of the gas molecules
A gas expanding from high pressure to lower pressure is known as the what?
Joule-Thompson Effect
What happens to temperature via the Joule-Thompson effect?
Joules=cools
Compression of a gas creates heat. What is the clinical significance of this?
Possible fire at the hanger yoke.
The reaction of CO2 in the soda lime ends with what substances?
CaCO3 + NaOH
What happens when you accidentally put wrong anesthetic gas in wrong vaporizer? HLH?
High-low-high.
If higher vapor pressure agent it placed in a lower vapor pressure agent delivery system, the concentration of the agent delivered to the patient will be higher than the dial says.
What happens if you put the wrong anesthetic in the wrong vaporizer? LHL?
- Low High Low
- If lower vapor pressure agent is placed in a high vapor pressure agent delivery system, the concentration of the agent delivered to the patient will be lower than the dial says.
