Chapter 4 Flashcards
Gas
Compressible substance, with no specific volume, that tends to assume the shape of a container. Molecules move about most rapidly in this state
liquid
Incompressible substance woth a constant volume thats assumes the shape of its container; molecules flow freely, but substantial cohesion prevents them from expanding as a gas would
Solid
Substance that has a definite shape and size; the molecules of a solid generally have very little mobility
Incidents involving gases are potentially
the most dangerous for emergency responders
Compressed Gas
Gas that at normal temperature, exists solely as a gas when pressurized in a container as opposed to a gas that becomes a liquid when stored under pressure
Liguefied Gas
Confined gas that at normal temperatures exists in both liquid and gaseous states
Combustible Gase Detector
Device that detects the presence and or concentration of predefined combustible gases in a defined area. May require additional features to indicate the results to an operator
Be cautious and alert to vapors from liquids as they may be
Contact hazards Inhalation Hazards Flammable Corrosive Toxic
Micron
is the unit of measure typically used to express particle size. Unit of length equal to one millionth of a meter
Physical properties
Properties that do not involve a change in the chemical idntity of the substance, but affect the physical behavior of the material inside and outside the container, which involves the change of the state of the material. Exmples include boiling point, specific gravity, vapor density, and water solubility
Vapor Pressure
The pressure at which a vapor is in equilibrium with its liquid phases for a given temperature; liquids that have a greater tendency to evaporate have higher vapor pressuress for a given temperature
The lower the boiling point of a material
the highr the vapor pressure will be
Boiling point
Temperature of a substance when the vapor pressure equals atmospheric pressure. At this tempeature, the rate of evaporation exceeds the rate of condensation. At this point, more liquid is turning into gas then gas is turning back into a liquid
Sublimate
Change directly from a solid into a gas without going into a liquid state in between
Vapor density
Weight of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure. A vapor density less than one indicates a vapor lighter than air; a vapor density greater than one indicates a vapor havier than air
Material with a vapor density less than one included
helium, neon, acetylene and hydrogen.
Most gases have a vapo density
greater than one
Common materials with a vapor density greater than one
Propane Hydrogen sulfide Ethane Butan Chlorine Sulfur dioxide
Solubility
Degree to which a solid, liqud, or gas dissolves in a solvent
Hydrodcarbon
Gasoline, diesel fuel, pentane
Polar solvent
alcohol, methanol, methylethylketone MEK, combine with water, the two liquids mix.
irritant agents that are water soluble usually cause
early upper respiratory tract irritation, resulting in coughing and throat irritation.
Partially water soluble chemicals will
penetrate into the lower respiratory system and casus delayed (12 to 24 hours) symptoms that include breathing difficulties, pulmonary edema and coughing up blood
Misciblilty
Two or more liquids’ capability to mix together