1 - Physics Review & Gas Laws Flashcards
1
Q
What force is exerted between molecules in liquid form?
A
Van der Waals forces
2
Q
How is “saturated vapor pressure” defined?
A
The pressure exerted by a vapor when, at any one temperature, an equilibrium is reached at which the same number of molecules are vaporizing as are returning to liquid.
3
Q
How is “boiling point” defined?
A
The temperature at which vapor pressure becomes equal to atmospheric pressure and at which all liquid changes to gas phase
4
Q
How are vapor pressure and boiling point related?
A
Inversely
5
Q
Define the unit “newton (N)”
A
The force that will give a mass of 1 kilogram an acceleration of 1 meter/second^2
6
Q
What is the formula for “force”?
A
F = ma (mass x acceleration; Newton’s second law)
7
Q
What is the formula for “pressure”?
A
P=f/a
8
Q
What is a pascal (Pa)? What units are generally utilized?
A
The pressure of 1 newton acting over 1 square meter - N/m^2;
kilopascal (kPa) and psi
9
Q
What is atmospheric pressure in bars?
A
1 bar
10
Q
What is atmospheric pressure in kilopascals?
A
100 kPa
11
Q
What is atmospheric pressure in mm of mercury?
A
760 mmHg
12
Q
What is atmospheric pressure in cm of water?
A
1034 cm H2O
13
Q
What is atmospheric pressure in psi?
A
14.7 psi
14
Q
What is 1 kilopascal in mmHg; cm H2O; psi?
A
7.5 mmHg; 10.34 cmH2O; 0.147 psi
15
Q
Fill in the blank: Absolute pressure equals ___________ + atmospheric pressure.
A
gauge pressure
16
Q
Give 3 examples of gauge pressure
A
Gas-cylinder pressures, art line pressures, ventilator pressures
17
Q
What is Boyle’s Law?
A
At a constant temperature, the volume of a given gas varies inversely with the absolute pressure
18
Q
Boyle’s Law formula
A
P1 x V1 = P2 x V2
19
Q
What is the constant in Boyle’s Law?
A
Temperature
20
Q
What is Charles’ Law?
A
At a constant pressure, the volume of a given gas varies directly with the absolute temperature
21
Q
What is the formula associated with Charles’ Law?
A
V1/T1 = V2/T2
22
Q
What is the constant in Charles’ Law?
A
Pressure
23
Q
What is absolute zero in Kelvin and degrees Celsius?
A
0 K and -273 degrees C
24
Q
What is another name for Gay Lussac’s Law?
A
3rd Perfect Gas Law
25
What is Gay Lussac's Law?
At a constant volume the absolute pressure of a given mass of gas varies directly with the absolute temperature.
26
What formula is associated with Gay Lussac's Law?
P1/T1 = P2/T2
27
What is the effect of low atmospheric pressure on boiling point?
Low atmospheric pressure leads to low boiling point
28
What is Dalton's Law of Partial Pressures?
In a mixture of gases the pressure exerted by each gas is the same as that it would exert if it was alone in the container.
29
What formula represents Dalton's Law of Partial Pressures?
P1 + P2 + P3 = Ptotal
30
What is Avogadro's Hypothesis?
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules (a mole).
31
What is Avogadro's number?
6.022 x10^23
32
What is STP?
Standard Temperature and Pressure with the following conditions: 0 degrees Celsius, 760 mmHg, dry (no water vapor)
33
How much volume does one mole of any gas occupy at STP?
22.4 liters
34
What is the Universal Gas Constant?
The gas laws combined with Avogadro's hypothesis
35
What is the formula for the Universal Gas Constant?
PV/T = universal gas constant (nR)
n: number of moles
R: constant
36
What is another name for the Ideal Gas Law?
Universal Gas Law
37
What is the formula associated with the Universal Gas Law?
PV = nRT
38
What is "critical temperature"?
The temperature above which no amount of pressure can liquify a gas
39
What is "critical pressure"?
The pressure to liquify a gas at its critical temperature
40
Upon what factors does the solubility of a gas in a liquid depend?
Partial pressure of the gas, temperature, type of gas, type of liquid
41
What is Henry's Law?
At a certain temperature, the amount of a given gas dissolved in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid.
42
What is Le Chatelier's Principle?
A change in any of the factors in determining an equilibrium causes the system to adjust or reduce or counteract the effect of the change (ex., solubility increases with decreasing temp)
43
What is a solubility coefficient?
The volume of gas which dissolves in one unit volume of the liquid at the temperature concerned
44
What is a partition coefficient?
The ratio of the amount of substance present in one phase compared with another (the two phases being of equal volume and in equilibrium)
45
Does the value given for a blood-gas coefficient represent the amount of solute dissolved in blood or in gas form?
The amount dissolved in blood; the amount in gas form is assumed to be 1
46
What is the "blood-gas partition coefficient"?
It reflects the proportion of the anesthetic that will be absorbed in the blood versus the amount of anesthetic that will leave the blood to diffuse into the tissues
47
Select the correct answer: Inhaled agents with (low/high) solubility leave the blood quickly and enter the tissues producing a rapid induction of anesthesia.
Low
48
What is the "oil-gas partition coefficient"?
The ratio of a gas present in oil versus in the gas state (lipid solubility). An indication of anesthetic potency.
49
What are three locations where diffusion takes place?
Gas-liquid barrier, gas filled area, membrane
50
Name 5 factors that influence diffusion
Thickness of membrane (d)~, size of molecule (MW)~, surface area of membrane (A)*, solubility of gas (S)*, and pressure gradient (P1-P2)*
*directly proportional
~indirectly proportional
51
What is Fick's Law?
The rate of diffusion of a substance across unit area is proportional to the concentration gradient (review the confusing equation on slide 33)
52
What 4 phenomena are explained by Fick's Law?
Concentration effect, second gas effect, diffusion hypoxia, and expanded air-filled spaces with nitrous
53
What is Graham's Law?
The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight (the bigger the molecule, the slower diffusion is)
54
What is the "second gas effect" with nitrous oxide?
Nitrous, due to its low solubility, is taken up in large volumes and thus accelerates the rate of rise of the alveolar concentration of the second gas in theory
55
How does nitrous oxide cause diffusion hypoxia?
Because of nitrous's low solubility, it is eliminated so rapidly that it dilutes the alveolar concentration, causing the PaO2 to drop
56
Why does nitrous oxide move into air-filled cavities?
Nitrous oxide has a blood-gas coefficient of 0.47, 34x greater than nitrogen's blood-gas coefficient at 0.014. As a result, nitrous can enter an air-filled cavity 34x faster than nitrogen can leave the cavity to enter the blood. This will call compliant cavity walls to expand and noncompliant barriers to burst.
57
What phenomenon is explained by the property of cohesion?
Surface tension in a glass of water
58
What property explains the tendency of water to have a concave meniscus in a thermometer?
Adhesion
59
What is the difference between cohesion and adhesion?
Cohesion is attractive force between like substances, and adhesion is attractive force between unlike substances.
60
What is the property of reduced by the presence of surfactant around alveoli that acts at the surface of a liquid to keep it in its most compact form?
Surface tension
61
What is the formula for pressure in liquids?
P = hd
| height of column x density weight of liquid
62
What is the conversion factor for mm Hg and cm H2O?
7.5 mm Hg = 10.2 cm H2O
63
What is the formula for flow?
F = Q/t
| Quantity, time
64
Describe laminar flow
Fluid movement in smooth layers with no turbulence or eddies, the least resistance; flow greatest at the center, slower at the walls of the channel
65
Describe turbulent flow
Flow not smooth with eddies and swirls; happens when critical velocity is reached, direction changed, diameter abruptly changed, or flow obstructed; resistance increased from laminar flow. Energy is lost, requiring a greater pressure gradient.
66
What factors impact resistance to flow?
Diameter of the channel (r), length of channel (L), nature of the flow (laminar vs. turbulent), and viscosity of fluid (n)
67
What is the relevancy of the Hagen-Poiseuille equation?
The derivative (Resistance = 8nL/πr^4) describes how viscosity, length of the channel, and radius impact resistance to flow
68
Which variable has the greatest impact on the Hagen-Poiseuille equation derivative?
Radius
69
What does Poiseuille's Law describe?
Flow rate in relation to resistance and the pressure gradient with ideal fluid and no turbulence; flow is directly proportional to pressure.
70
What is the formula for Poiseuille's Law?
P1-P2 = Resistance x Flow
OR
Flow = P1-P2/8nL/πr^4
71
What is the Bernoulli Effect?
Given a channel with a narrowing which then increases, the pressure measured along the channel is lowest at the narrowest point, often below atmospheric pressure. Narrowing causes increased velocity/kinetic energy and decreasing potential energy.
The decreased pressure at the narrowing allows for entrainment in the Venturi system.
72
What is Laplace's Law?
The relationship of wall tension (T), pressure (P) and radius of cylinders/spheres
73
What formula represents Laplace's Law in cylinders? Spheres?
T = Pr; 2T = Pr
74
What is a calorie?
The energy needed to increase the temperature of one gram of H2O 1 degree Celsius
75
How many joules in 1 kcal?
4184 joules - increases 1 kg H2O (d/t kcal, not cal)
76
Conversion factor for Fahrenheit to Celsius and vice-versa? Celsius to Kelvin?
F-->C: T = 5/9(F-32)
C-->F: T = 9/5C+32
C-->K: T=C+273
77
What is the triple point and at what temperature does it occur?
The temperature at which water, ice, and water vapor are all in equilibrium; at 0 degrees Celsius or 273.15 Kelvin
78
What is the first law of thermodynamics?
Heat is a form of energy and can be converted to other forms of energy, but neither created nor destroyed
79
What is the second law of thermodynamics?
Heat always flows from warmer to cooler. There must exist a difference in temperature and the two things must be in contact (whether by air or otherwise).
80
What are the 4 methods of heat transfer?
Radiation, evaporation, convection, and conduction
81
List the methods of heat transfer in order of relevance to the OR setting from most to least
Radiation (40%)>>Convection (32%)>>Evaporation (28%)>>Conduction (2%)
82
What is "specific heat capacity"?
The amount of heat required to raise the temperature of 1 kg of a substance by 1 Kelvin (water being the standard)
83
How many joules in 1 calorie?
4.18 joules
84
What is heat capacity?
The amount of heat required to raise the temperature of an object by 1 Kelvin.
Heat capacity = mass of object x specific heat capacity
85
What is the approximate mean specific heat capacity of human tissue?
3.5 kJ/kg/degrees C
86
What is the heat production from shivering?
240 W or 240 x 60 joules/min
87
What is "specific latent heat"?
The energy required to convert 1 kg of a substance from one phase to another at a given temperature (J/kg)
88
What is the "latent heat of fusion"?
The heat required to change a solid to a liquid
89
What is the "latent heat of vaporization"?
The heart required to change a substance from a liquid to a gas at a constant temperature
90
What is an example of the Joule-Thompson effect?
Nitrous cylinder cooling as it empties rapidly, freezing water vapor on the outside (joule is cool)
91
What is a beta particle in the context of radiation?
An electron
92
What is an alpha particle in the context of radiation?
2 protons and 2 neutrons
93
Describe ionizing electromagnetic radiation
Energy is released by removing electrons from atoms in tissues, creating cations that are very chemically reactive and hazardous (examples, x-rays and gamma rays released by radioactive isotopes; used in cancer treatment and for surgical dissection)
94
Describe nonionizing electromagnetic radiation
Discharges energy without creating ions or removing electrons from atoms in tissues; includes infrared radiation, visible light, ultraviolet radiation (LASER - light amplification by stimulated emission of radiation)
95
What is the relationship between distance and intensity of radiation received?
Inverse; distance is the best form of protection (3-6 feet)
96
What are two other methods to protect from radiation?
Minimize time around radiation (like with fluoroscopy); implement shielding (lead aprons, shields [0.25-0.5 mm lead sheeting blocks most scattered radiation])
97
Does distance protect from laser exposure?
NO; wear laser-specific eyewear and use nonreflective instruments
98
What is the best practice to prevent surgical smoke inhalation?
An efficient smoke evacuator
99
What is the smoke debris size range? What size particles do surgical masks filter?
0.1-0.8 um; 3 um (not sufficient protection)
100
What is the mass of one mole of hydrogen?
2 gm
101
What is the mass of one mole of oxygen
32 gm
102
What is the mass of one mole of carbon dioxide?
44 gm
103
What is the mass of one mole of nitrous oxide?
44 gm
104
What is the critical temperature of nitrous oxide?
36.5 degrees Celsius
