Gas Laws Flashcards
cummulative information for exam 2
What are the vales for :
Absolute pressure and temp
Room pressure and temp
Body temp
Absolute – 273.15 K 0 C @ 1 atm
Room - 293K 20 C @ 1 atm
Body - 310K 37 C @ 1 atm
Law— at a constant temperature, the volume of a given mass of gas varies inversely with the absolute pressure ?
Boyle’s Law
P1V1 = P2V2
What is constant in Boyle’s law?
Temperature: “Boyle had TB”
Formula for ideal gas law?
PV=nRT (NOTE: Pressure and Temp are Absolute)
use to derive the 3 gas laws
P = pressure
V = volume
n = number of moles
R = ideal gas constant
T = temperature
What is an example of applying Boyle’s law?
calculating the amount of oxygen available at 1 atm
1 atm = _____ kPa
1 atm = 101.33 kPa 1 atm ~ 100 kPa
What is the water capacity of an E cylinder?
4.8 L
1 atm = _____ psi
14.7 psi
Law — at a constant pressure, the volume of a given mass of gas varies directly with the absolute temperature?
Charles’s Law
What is the contant in Charles’s Law?
pressure; “Charles had CP”
Law— at a constant volume, the absolute pressure of a given mass of gas varies directly with the absolute temperature?
Don’s Law
What is constant in Don’s Law?
volume; “Don had VD”
When given a problem to solve, how do you decide which gas law to use?
- set the variables = to the constants 2. drop the constants 3. use given variables to solve for the unknown variable
What is STP?
Standard Temp and Pressure T= 273 K, 0 C P= 760 mmHg
What is RTP?
Room Temp and Pressure T= 293 K, 20 C P= 760 mmHg
What is BTP?
Body Temp and Pressure T= 310 K, 37 C P= 760 mmHg
A fire breaks out in the dental office near the nitrous tank storage room, what could happen to the tanks? why?x
a. explode b. heat would cause the gas to expand, therefor increase pressure with in the tank
How does the cryprobe work?
adiabatic process
What is adiabatic process?
altering the state of gas without allowing the gas to exchange heat energy with it’s surroundings. Adiabatic heating = rapid pressure increase(compression) Adiabatic cooling = rapid pressure decrease (expansion)
Law— in a mixture of gases the pressure exerted by each gas is the sames as that which it woudl exert if it alone occupied the container?
Dalton’s Law of Partial Pressure
How is the ideal gas law applied to partial pressures?
The ratio of partial volumes to partial pressures is equal and equals the ratio of total volume to total pressure
What type of problem might Dalton’s Law be used in ?
calculating the partial pressure of O2 against partial pressure of N2O in the same tank
What is the pressure inside the O2 E cylinders used in the hospital?
1900 psi(g)
What is the volume in O2 E cylinders that we use at the hospital?
660 L
What is the relative nominal cylinder pressure at constant temp 15 C in an O2 E tank?
137 bar
What is the relative contents (in L) at constant temp 15 C in an O2 E tank?
680 L
What idea can be used to calculate the real values of compressed gases as compared to Boyle’s law?
van der Waals forces
What is water vapor pressure at 37 C? (in mmHg)
47 mmHg
What is water vapor pressure at 37 C? (in kPa)
6.3 kPa
Formula for alveolar partial pressure devired from ETCO2
PACO2 = [(Ambient pressure - H2O vapor pressure) x CO2 concentration]/100
example : ETCO2 = 5.6 %
PACO2 = [(101.3 kPa - 6.3 kPa)(5.6%)] = 5.3 kPa which = 40 mmHg
State Avogadro’s hypothesis
equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
What is avogadro’s number?
1 mole = 6.022 X 1023 molecules
1 mole at STP (standard) occupies how much volume?
22.4 L
1 mole at RTP (room) occupies how much volume?
24 L
1 mole at BTP occupies how much volume?
25.4 L
what happens to CO2 (at RTP) that was insuflated into adbomen?
expands d/t body temp
What is the PAO2 at the following FiO2 :
.21
.50
1
PAO2 @ 0.21 = 100 mmHg
PAO2 @ 0.50 = 300 mmHg
PAO2 @ 1 = 663 mmHg
state the formula for Alveolar Oxygen Equation
PAO2 = FiO2(PB - PAH2O) - (PACO2/R)
PAH2O = 47 mmHg (vapor pressure)
PACO2 = 40 mmHg
What is critical temp?
temperature above which liquification does not occur
what is critical pressure?
the pressure (= vapor pressure) at the critical temperature
what is the critical temp of nitrous oxide
36.5 C
When would you be able to use boyle’s law to calculate the pressure in a nitrous oxide tank?
when all the liquid is gone (1/4 full) gas pressure only in the tank a745 psi(g)
what is the definition of a gas
a substance above its critical temperature
(i.e. O2, N2 at RTP)
what is the definition of a vapor?
A susbstance in a gas like state but below it’s critical termperature
(i.e. N20, CO2, Sevo @ RTP)
what allows the pressure out of N2O tank that has been exposed to increase temperatures
temperature dependent fusable plugs
how do you calculate filling ratio
mass of gas (kg) / mass of H20 that would fill cylinder
1 L H20 = 1 kg
for mass of gas, add atomic weights
Mass of gas (kg) / volume of cylinder (L)
Filling ratio in the US
0.68
Filling ratio in the UK
0.75
What is the tare (empty) weight of an E cylinder? H Cylinder?
E = 14 kg
H = 119 kg