Flashcards in Physics and Chemistry Deck (49)
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1
The closer the vapor pressure is to atmospheric pressure, the more easily it _____.
boils
*this is why desflurane is placed in a heated vaporizer
2
Vapor pressure is a function of _______.
temperature
3
The % concentration of any gas is found by _______.
dividing the pressure of the gas over the total pressure. (760 for 1 atm)
4
If halothane was added to an isoflurane vaporizer, what would happen to the delivered concentration? halothane added to sevo?
added to iso: it would be about the same because the VP of halothane is 244 and Iso is 240mmHg
added to sevo: the delivered concentration would be more than what was dialed because the VP of halothane is 244mmHg versus Sevo VP of 170mmHg
5
To remember what happens to a volatile agent that was added to the wrong vaporizer, just remember:
HLH
LHL
HLH= if a HIGHER VP agent is placed in a LOWER VP vaporizer, the concentration will be HIGHER
LHL= if a LOWER VP agent is placed in a HIGHER VP vaporizer, the concentration will be LOWER
6
Desflurane vaporizer is heated to _____. What is the vapor pressure at this temperature?
39 degrees C; approximately 2 atm or 1500mmHg
7
Name some units of pressure.
mmHg, cm H2O, atm, psi, kPa, bar
8
What is the conversions for the following:
mmHg--> cm H2O
atm--> mmHg--> psi--> kPa--> bar
psi--> mmHg
1 mmHg= 1.36 cmH2O
1 atm=760 mmHg=14.7 psi=101 kPa= 1 bar
1 psi= 54 mmHg
9
What type of gauges measure high pressures?
Bourdon gauge
measures the pressure relative to atmospheric pressure, not the absolute pressure--> when it reads 0... the pressure inside is equal to the atmosphere
10
Define tension.
"force" along a straight line
11
T= P x r is what law?
Law of LaPlace
as a structure expands (ie: radius increases-->cylindrical-- blood vessel), the tension (force) in the wall of the structure increases
12
In regards to the Law of LaPlace.... If you have a small soap bubble on one end of a straw and a large one on the other end, what will happen?
The small one will collapse because it has a greater pressure
*this is ONLY true when there is a liquid-air interface..... this happens in ARDS, when smaller alveoli collapse due to lower than normal surfactant and empty into alveoli with lower pressures--> causing atelectasis
** normal alveoli with normal surfactant--> tension would increase with the radius
13
According to Poiseuille's Law, doubling the radius increases flow _____ times.
16 times
tripling the radius= increases flow 81 times
halving the radius= decreases flow to 1/16th of original
14
Changing what single factor, according to Poiseuille's Law, has the most impact on flow?
the radius
15
What property of a fluid determines flow, when flow is laminar?
viscosity
16
When does flow become turbulent?
If:
1) velocity of flow is high
2) tube wall is rough (corrugated)
3) kinks, bends, narrowing, or branches (RAE tube)
4) fluid flows through an orifice
*does not become turbulent when flowing through an angled tube if the angle is <25 degrees
5) reynolds # exceeds 1500-2000
17
Resistance to flow ______ when flow becomes turbulent.
increases
18
What explains why the temperature of a cylinder of compressed gas decreases as the gas is released?
Joule-Thompson effect
19
How to remember the common gas laws???
Can the gay people possible b---- v-----.
20
What is the generalized ideal (universal) gas law?
PV=nRT
where P= pressure, V=volume, T=temperature, n=moles of gas, and R=universal gas constant
21
One ____ is the molecular weight of a substance in grams.
mole
22
_______ described the relationship between the amount of gas and volume of gas.
Avogadro
23
What is Avogadro's number?
the number of molecules in one mole of a substance is 6.022 x 10 to the 23rd
24
What was Avogadro's hypothesis?
one mole of gas at standard temperature (0C) and standard pressure (1atm) occupies a volume of 22.4 liters
25
2 moles of gaseous N2O occupy what volume under standard conditions?
22.4 x 2= 44.8 liters
26
What is critical temperature?
gases liquefy if sufficient pressure is applied and the temperature is below a critical value called the critical temperature
ex) critical temperature of N2O is 36.5C, so it can be compressed and stored as a liquid at room temperature
ex) critical temperature of O2 is -119C, O2 cannot be liquefied at room temperature no matter how much pressure is applied
27
Adiabatic means______.
heat cannot be dissipated ("constant heat")
28
What is the Joule-Thompson effect?
"Joule is Cool"
when compressed gas is allowed to escape freely into space, the process is adiabatic and cooling occurs (explains why condensation forms after opening a valve)
29
At 20C, a full E-cylinder of O2 has a pressure of ~ _______psi and contains approximately ______L.
1900-2200psi; 660L
30
