CH.6 Physical Principles of RT Care Flashcards
Three primary states of matter
solids, liquids, gases
Solids
–have high degree of internal order
–fixed volume and shape
–strong mutual attractive force between atoms
–molecules have the shortest distance to before collision
– motion referred to as jiggle
Liquids
–have fixed volume, but adapt to shape of their container
–atoms exhibit less degree of mutual attractions
—-shape is determined by internal and external forces
Gases
–no fixed volume or shape; weak attractive forces
–exhibit rapid, random motion with frequent collisions
Plasma
–fourth state of matter
–combination of neutral atoms, free electrons, atomic nuclei
–can react to electromagnetic forces and flow freely like liquid or gas
–not relevant to practice of respiratory care
Two major types of internal energy
Potential and Kinetic energy
Potential energy
– energy of position attractive forces between molecules
–weak in gas state
–makes up most of internal energy in solids and liquids
Kinetic energy
–Energy of motion
–makes up most of gases internal energy
Thermodynamics
–the science studying the properties of matter at various temperatures
–the kinetics speed of reactions of matter at various temperatures
1st law of thermodynamics
–energy cannot be created nor destroyed only transferred or change
2nd law of thermodynamics
–heat energy can move from areas of higher temperature to low temperature spontaneously but if moving from low to high it muse use energy
Heat Transfer
–when two objects of different temperature coexist, heat will move from hotter to cooler object until both are equal
Heat Transfer: Conduction
–main method of heat transfer in solids via direct contact between molecules
Heat Transfer: Convection
–mixing of molecules at different temperatures, transfers heat in liquids and gases.
Heat Transfer: Radiation
–radiant heat transmitted using waves or particles
Vaporization
–the change of state from liquid to gas
Boiling Point
–heating liquid to temperature at which its vapor pressure exceeds atmospheric pressure
Evaporation
–change of state from liquid to gas, or gas to liquid at temperature below its boiling point
–form of vaporization where heat is taken from the air surrounding the liquid,
– example: cooling the car
Condensation
– a gas turns back into a liquid
–opposite of evaporation
Temperature
–measurement of heat
–gas temperature is directly proportional to its kinetic energy
Absolute zero
–lowest possible temperature that can be achieved
–temperature at which there is no kinetic energy
–molecules cease to vibrate; object has no measurable heat
Fahrenheit and Celsius
–based on property of water
–0 C is freezing point of water
– -273 C= kinetic molecular activity stops= 0 K
Kelvin scale
–based on molecular motion
–used by SI units
–zero point= to absolute zero
Conversions
– K= C+273
– C= 5/9 (F-32)
– F= 9/5 C+32
Freezing
–opposite of melting
–Freezing point: temperature at which substance freezes
Melting
–changeover from solid to liquid state
–Melting point: temperature at which melting occurs
Sublimation
–transition from solid to vapor without becoming liquid as an intermediary form
–occurs because vapor is low enough
Properties of Liquids: Pressure
–depends on height and weight
Properties of Liquids: Buoyancy
–occurs because pressure below submerged objects always exceed pressure above
Properties of Liquids: Specific Gravity
–ratio of density of one fluid when compared with density of another reference substance
Properties of Liquids: Viscosity
–force opposing fluid’s flow
–blood has viscosity five times greater than water
–the stronger the cohesive forces, the greater the fluid viscosity
Properties of Liquids:Cohesion
–attractive force between Like molecules
Properties of Liquids: Adhesion
–attractive force between Unlike molecules
Properties of Liquids: Surface tension
–force exerted by like molecules at liquid’s surface
Pascal’s Principle
–states that a confined liquid transmits equally in all directions
–liquid pressures depend only on the height and not the shape of the vessel or the total volume of the liquid
Laplace’s Relationship
–states that the tension of the wall of a sphere is the product of the pressure times the radius of a chamber, the tension is inversely related to the thickness of the wall
Capillary Action
–is the basis for blood samples obtained by use of a capillary tube
–the absorbent wicks used in some gas humidifiers are also an application if the principle, as are certain types of surgical dressings
Water Vapor Pressure
–when water is converted to vapor, it acts like gas
–water vapor pressure represents the kinetic activity of water molecules
Humidity
–measurement of the water vapor content
Absolute humidity
–the actual amount of weight of water vapor in gas
–water vapor content
–measured in mg/L
–varies with temp and pressure
–air that us fully saturated with water vapor has absolute humidity of 43.8 mg/L at 37 C.
Gas Density
–is the ratio of gas’s mass to its volume
Dalton’s Law
–Gas pressure
–Partial pressure= pressure exerted by single gas in a gas mixture
–Dalton’s Law= partial pressure of gas in mixture is proportional to its percentage in mixture
–the total pressure exerted by a mixture of gases is equal to the sum of the pressures exerted by the individual gases if they were present alone
Henry’s Law
–the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid
–gases can dissolve in liquids
–example=carbonated water and soda
Boyle’s Law
–volume of gas varies inversely with its pressure
–describes gas behavior under constant temperature. The temperature of an ideal gas should not change with either expansion or contraction
–volume of a gas varies inversely with its pressure
–with constant temperature, the volume and pressure are directly proportional
–example: breathing
Charles’ Law
–volume of gas varies directly with its temperature
–higher temp= more volume
–Lower temp= lower volume
–at a constant pressure, the volume of gas is directly proportional to its temperature
Gay-Lussac’s Law
–pressure exerted by gas varies directly with its absolute temperature
–example: tires
Hydrodynamics
–study of fluids in motion
Flow resistance
–is the constant of proportionality for an assumed linear relation between the pressure difference between the two points along the tube and the flow
Fluid dynamics: Pattern of flow
Laminar
turbulent
transitional
Laminar Flow
–fluid moving in discrete cylindrical layers or streamlines
Turbulent flow
–loss of regular streamlines, fluid molecules form irregular eddy currents in chaotic pattern
Transitional Flow
–is a mixture of laminar and turbulent flow
Volume of a gas
–dissolves in a liquid equals its solubility coefficient times its partial pressure; higher temperatures decrease gas solubility, and lower temperatures increase gas solubility
Bernoulli principle
–when the flow of gas increases, the pressure downstream will decrease
– the venturi effect is an application of Bernoulli’s principle using gases
