Chemistry Flashcards
Graham’s Law
Grahams Law
The rate of diffusion of gas is inversely proportional to the square root of the molecular weight
- the heavier the molecule the slower the diffusion
Nitrous critical temperature
36.5
What does cooling do to vapor pressure?
COOLING DECREASES VAPOR PRESSURE
- more molecules enter liquid phase than gas
What can show you Reynold’s number in the machine?
Massie: I want to see the flow become turbulent
float bob?? on the meter goes crazy when you are turning your flow up.

Guy Lussac’s Ideal Gas Law
Guy Lussac’s Ideal Gas Law
The pressure of gas varies directly with the absolute temperature when the volume is kept constant
- when the temperature of a gas in a container at constant volume increases, pressure increases and vice versa.
What is an example of the Law of LaPlace (for cylinders)
APPLICATIONS
- A capillary wall will withstand a pressure of 100 mmHg better than a vein because the capillary has a tiny radius c/t a vein(perhaps 1 millionth that of a vein), SO the tension in the wall of the capillary is extraordinarily smaller than that in the vein
- Heart (cylinder): the greater the filling of the ventricle, the greater the tension in the ventricular wall
i.e.: the tension in the wall of the heart is increased when filling is increased

Diffusion rate of gas is directly proportional to?
a. Partial pressure gradient (P1-P2)
b. membrane area
c. Solubility coefficient of gas membrane
T/F
A gas cannot be liquefied if the temp is above the critical temp regardless of the pressure applied.
True
Critical Temperature
gases liquefy if sufficient pressure is applied and the temperature is BELOW critical temperature
Simultaneous administration of slow agent (volatiles) and faster agent (N2O) speeds the onset of slower volatile
SECOND GAS EFFECT
Daltons Law/ Henry’s Law
To estimate the PAO2 (alveolar) in a healthy patient, multiply the percent inspired O2 by 6
Estimate PA02, PaO2, and the PAO2- PaO2 gradient if the patient is breathing an FiO2 of 0.6 (60%)
PAO2= 60 X 6 = 360
PaO2 = 60 x 5 = 300
360 -300 = 60
The estimate PAO2 -PaO2 should be equal to inspired FiO2
Boyle’s Law
What is a clinical application?
P1V1 = P2V2
Clinical Applications:
- If a pressurized cylinder is opened and slowly emptied so that temperature does not change, the volume of gas released from the cylinder can be estimated by Boyle’s Law.
- A full E cylinder of O2 at 2100 psi with 4.46 liters (a small volume of gas under high pressure) will release into the atmosphere about 625 liters at 14.7 psi (1 atm) (a large volume of gas at low pressure).
- Boyle’s Law explains why a large volume of gas is released from a pressurized cylinder

What is the description of the Law of LaPlace?
Why is it important?
What is a pathophysiological example?
- The tangential tension in the wall of a hollow structure is proportional to the internal pressure and to the radius
- Tension may be defined as the internal force generated by a structure
- The greater the radius in a chamber or vessel, the greater the tension in the walls of the chambers or vessels
- Aneurysm

The heavier the molecule the slower it will take to get to that membrane
Graham’s Law of diffusion
Diffusion rate is inversely proportional to
a. Membrane thickness
b. The square root of MW
What is the main determinant of diffusion of any gas with all other factors equal
CONCENTRATION GRADIENT
Full E cylinder pressure on 20 C
Full E cylinder pressure on 20 C
1800-2200 psi
Henry’s Law
The amount of O2 that dissolves in blood is 0.003 ml/ 100 ml blood/ mmHg partial pressure
Critical Temperature (CT)
A gas cannot be liquified if the temperature is above the critical temperature, regardless of the amount of pressure applied
The formula for Reynold’s number
When Reynolds number exceeds 1500 - 2000 flow changes from __ to __
Re= (vdp)/n
When Reynolds number exceeds 1500 - 2000 flow changes from laminar to turbulent
The formula for Law of LaPlace (cylinder)
Law of LaPlace (cylinder)
T= change in P x r
= the greater the radius in a chamber or vessel the greater the tension in the walls of the chamber or vessels
What is Bernoulli’s effect?
What are some perfect examples?
- When fluid flows through a constricted region of tube (Venturi tube), the velocity of flow increases (visualize a narrowing in a stream) and the lateral pressure (the pressure exerted by the fluid on the walls of the tube) decreases
- Increased pressure, decreased flow, and vice versa
- i.e.: Nebulizer, venturi O2 mask, jet ventilator/injector all entrain air (suck air in from atmosphere because pressure so low –> Venturi principle
Boyles Law
Boyles Law
at any given temperature (constant) , the value varies inversely with the pressure
P1VI- P2V2
Example of Joule- Thompson effect
Joule- Thompson effect
Adiabatic process in which colling occurs when compressed gas is allowed to escape freely from space
i.e : why a cylinder cools and condensation forms after opening the valve
How many times more CO2 and N2O are more diffusable than O2?
CO2 and N20 are both = 20 times more diffusible than O2
What is the property of a fluid that determines flow when the flow is LAMINAR?
VISCOSITY
How much CO2 is dissolved in arterial blood when PaCO2 is 50 mmHg?
To calculate the amount of CO2 that dissolves in blood multiply the partial pressure of co2 BY 0.06
50 X 0.06 =3.0 ml CO2/ 100 ml blood
What does heat do to vapor pressure?
HEAT INCREASES VAPOR PRESSURE
- more molecules enter gas phase than liquid
Ideal Gas Law Clinical Application
Ideal Gas Law
As a cylinder compressed gas empties, the pressure in the cylinder falls (because the number of the moles (n) in the tank is decreasing
– remember a cylinder has constant volume, when the cylinder is emptying the amount (moles) if gas is decreasing
Metric Conversions

How much does a full cylinder of N2O contain
L
PSI
N20 = 1590 L @ 725 -750 psi
Diffusion Hypoxia is important when?
emergence
during emergence, when high concentrations of a rapid anesthetic (N2O) are given, agent exits quickly through lungs and replaced by less soulble nitrogen in air.
-
What is the pressure for O2 E- Cylinders? on what temp?
what is the capacity?
1800 -2200 psi
20 C
625 -700
Full E cylinder capacity on 20 C
Full E cylinder capacity on 20 C
625 - 700 L
Charles Law Clinical Applications
Charles Law Clinical Application
- The inflatable cuff of an ETT and LMA expands when places into an autoclave for sterilization
- Helium Balloon
Formula for Ideal Body weight Brocca

Why does N2O lead to an increase in volume (or pressure) in gas spaces?
- Air spaces rich in nitrogen which is 34-36 times less soluble than N2O N2O expands space then exits quickly, leaving nitrogen
*ficks law
What may result in diffusion hypoxia?
May result in transient dilution of O2 and CO2
Oxygen critical temp
-119 C
Law of LaPlace formula (spheres)
Clinical significance?
Law of LaPlace formula (spheres)
T= Pr/2
- Tendency of the smaller alveoli to empty into larger alveoli is reduced –> atelectasis in ARDS
Gases with high molal capacities are called?
What is an example?
Quenching gases
CO2
What is the critical temp of Nitrous Oxide?
what happens if the temperature rises about room temp?
Critical Temp : 36.5 C
- since above room temp, let liquified; if rises above room temp, become gaseous
E cylinders have pressure of 745 psi @ temp 20 C with a capacity of 1590
N2O is how many times more diffusable than N2?
N20 is 34-36 times more diffusible than N2
- should not be used when there are air-containing cavities in the body (air embolism, pneumothorax)
What is the clinical application of Fick’s law?
FICKS LAW OF DIFFUSION
- The concentration-effect: initially, higher concentration of volatile than necessary (loading dose) delivered to speed –> over pressurizing
- The second gas effect: simultaneous administration of slow agent (volatiles) and faster agent (N2O) speeds onset of slower volatile
- Diffusion hypoxia
How much O2 is dissolved if FiO2 is 40 %?
If inspired O2 is given , estimate the PaO2 by multiplying the inspired concentration by 5
40 x 5 = 200
Also known as London dispersion forces
Van der Waals Forces
Overpressurizing
higher concentration of volatile than necessary (loading dose) delivered to speed initial uptake
What can be a pathophysiological example?

- Alveoli are spherically shaped; must look at normal alveoli and alveoli deficient in normal surfactant (i.e.: ARDS, EMPHYSEMA, BRONCHIOLITIS, COVID?)
- the smaller the radius the greater the pressure inside the bubble

How much does dissolved O2 increase in the blood when PaO2 increase from 100 to 500 mmHg
100 mmhg x 0.003 = 0.3 ml O2/ 100 ml blood
500 mmHg x 0.003 = 1.5 ml O2/ 100 ml blood
dissolved O2 increased by 1.2 ml O2/ 100 ml blood
How much O2 is dissolved in arterial blood when the PaO2 is 300 mmHg?
Henrys Law
300 mmHg x 0.003= 0.9 ml O2/ 100 ML blood mmHg
Second gas effect is important when?
induction
Formula for Adjusted Body Weight

Bernoulli effect
Bernoulli Effect
When fluid flows through a constricted region of the tube the velocity of the flow increases and the lateral pressure decreases.
–> Nebulizer, venturi O2 mask, jet ventilator /injector all entrain air (suck air in from atmosphere because pressure is low) –> VENTURI Priciple
Nitrous e-cylinder capacity at 20C
1590 L
if you increase the radius, what gets increased?

you increase the flow.
Flow is directly proportional to pressure and radius

What is Ficks Law?

What is the property of a fluid that determines flow when the flow is TURBULENT?
DENSITY
Reynold’s number
Formula for Ideal Body Weight

Nitrous e-cylinder pressure at 20C
Nitrous e-cylinder pressure at 20C
745 psi
Charles Ideal Gas Law
Charles Ideal Gas Law
The volume of any gas kept at constant pressure varies directly with the absolute temperature
- when temperature increases volume of gas increases and vice versa –
Boyles Law Clinical Application
Boyles Law Clinical Application
- Squeezing ambu bag (increase pressure, decrease volume)
- Inspiration on spontaneous breathing
- Measurement of FRC by body plethymography
What happens to small alveoli in a normal lung?
why?

Small alveoli DO NOT empty into large alveoli in normal lungs
- surfactant-
Pressure =
1 mmHg = _____ cm H2O
1 atm = _____ mmHg = _____ psi
1 psi ____ mmHg
Atmospheric pressure at sea level = 760 mmHg or ____ cm H20
Pressure = force per unit area
1 mmHg = 1.36 cm H2O
1 atm = 760 mmHg = 14.7 psi
1 psi = 54 mmHg
Atm at see level = 760 mmH or 1034 cm H20