Equations Flashcards
What is the equation for Boyle’s Law?
PV = K OR V ∝ 1/P
(Pressure, Vol, Konstant)
What is Boyle’s law?
If temp of gas is constant then pressure & vol are inversely proportional
What is the equation for Charles’ law?
V/T = K OR V∝T
(Vol, Temp, Konstant)
What is Charles’ law?
If pressure of a fixed mass of gas is constant then vol & temp are proportional
What is Gay-Lussac’s law and what is it also known as?
- Third gas Law
- If the vol of a fixed mass of gas is constant then the pressure & temp are proportional
- Applied to the filling of N2O cylinders
What is the equation for Gay-Lussac’s law?
P/T = K OR P∝T
How is the filling ratio calculated?
Weight of fluid in cylinder / weight of H2O required to fill cylinder
What is Avogadro’s equation?
V/n = K
(Vol, Konstant, amount of substance of gas)
What does Avogadro’s equation mean?
Equal volume of gases at same temp & pressure contain same no. of molecules regardless of structure/properties
What is the universal gas equation?
PV = nRT
( Pressure, Vol, no. moles of gas, gas constant, temp)
What is the universal gas equation a combination of?
Avogadro’s law & Charles’ law
What is the equation for Dalton’s law?
P.total = P.gas(a) + P.gas(b)
What is Dalton’s law?
In a mixture of gases the total pressure is always equal to the sum of the individual partial pressures of gases.
What is Henry’s law?
At constant temp, the mass of a gas that dissolves in a given type & vol of liquid is directly proportional to the partial pressure of that gas in equilibrium with the liquid
What is an application of Henry’s law?
- Volatiles: pp of anaesthetic in blood is proportional to pp of anaesthetic in alveoli
What’s the equation for Graham’s law of diffusion?
Rate of diffusion = 1 / √MW
(Molecular weight)
What is Graham’s law?
- The rate of diffusion of a gas is inversely proportional to the root of a molecular weight
- E.g larger the molecule the slower it diffuses
- Example: 2nd gas effect
What is the Hagen- Poiseuille equation?
Q = πPr4 / 8nl
(Flow(Q), pressure, radius, viscosity(n), length)
What is the Hagen-Poiseuille principle?
- Characteristics of laminar flow through a tube
- As pressure differential along tube increases so does flow.
- Only applies to Newtonian fluids
What is the equation for Reynold’s number?
Re = pvd / n
(density, velocity, diameter, viscosity(n))
What does Reynold’s number describe?
Factors that determine the critical velocity when flow becomes turbulent
What is the equation for Laplace’s law?
T = PR / 2t. OR P = T / R
(Tension, pressure gradient, radius, wall thickness(t))
What does Laplace’s law explain?
As the radius of a tube/sphere increases the pressure gradient decreases but as surface tension increases the pressure increases
What is Bernoulli’s equation?
P + 0.5pv2 + pgh = constant
(Pressure(P), density(p), velocity, acceleration(g), height)
What is entrainment ratio?
ER = Entrained flow / driving flow
What’s the equation for Ohm’s law?
V = IR
(voltage, current, resistance)
What does Ohm’s law state?
The electrical current is directly proportional to the potential difference applied.
How is capacitance calculated?
F = C/V
(Farad/capacitance, Coulomb, Voltage)
What is the equation for inductance?
H = Wb / A
(Inductance, Weber/magnetic field, amp)
What is the equation for work done?
W = F x D
(Work, Force, distance)
How is charge calculated?
Q = I x T. or Q = C x V
(Charge, Current, Time) or (Charge, capacitance, voltage)
What is the Beer-Lambert equation?
A = ɛdc
(Absorbance, extinction coefficient(ɛ), path length, conc)
What is the Beer-Lambert Law?
- The transmission of light through a substance is inversely proportional to its molar conc & thickness
What is the equation for natural frequency?
NFa D/√LCd
(natural frequency, catheter diameter, length, compliance, density)
What is the wave equation?
V = f x λ
(Velocity, frequency, wavelength)
What is the equation for volume of distribution?
Vd = X / C
(Vol, Amount of drug, plasma conc)
What is the equation for clearance?
Cl = K x Vd
(Clearance, rate constant, vol of distribution)
How is O2 delivery calculated?
Delivery = FiO2 x MV
How is O2 content calculated?
CaO2 = Hb x Sats x 1.34 + PaO2 x 0.023
Content = amount in plasma + amount bound to Hb
How is the amount of O2 bound to Hb calculated?
Hb x Sats x Hüfners constant (1.34)
What is the alveolar gas equation?
PaO2 = FiO2(P.at - P.H2O) - PaCO2/0.8
How is rate of elimination calculated?
Conc x clearance
How is vol of distribution calculated?
Vd = Dose / Conc
How is 1/2 life calculated?
half life = 0.69 x time constant
How is elimination rate constant calculated?
K = 1/ time constant
How is clearance calculated?
Clearance = Vd x K
How is loading dose calculated?
LD = Vd x target conc
How is maintenance infusion rate calculated?
Rate = target conc x clearance
