Chapter 2 — Understanding How Matter Behaves
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Questions and Answers

What occurs to heat during a change of phase?

  • Heat is absorbed only when a substance freezes.
  • Heat enters or exits the material depending on the direction of the change. (correct)
  • Heat does not play a role in phase changes; only physical proportions change.
  • Heat is always added to the material regardless of the phase change.

    • Which statement correctly describes the relationship between melting point and freezing point?

  • The melting point and freezing point can vary widely depending on external pressure conditions.
  • The melting point is typically lower than the freezing point.
  • The melting point and freezing point are usually the same or similar for a substance. (correct)
  • The melting point is generally different from the freezing point for all materials.

    • What unique behavior does water exhibit when it freezes?

  • Water stays the same volume as it was in liquid form.
  • Water becomes denser and sinks.
  • Water freezes at temperatures higher than its melting point.
  • Water expands and can rupture containers due to pressure. (correct)

    • What defines the standard boiling point of a liquid?

    <p>The temperature at which the vapor pressure is equal to 1 atmosphere.</p> Signup and view all the answers

    How do molecular weight and flash point relate?

    <p>Higher molecular weight substances tend to have higher flash points.</p> Signup and view all the answers

    What does evaporation refer to in the context of liquid phases?

    <p>Change of a liquid to vapor at temperatures below its boiling point.</p> Signup and view all the answers

    What influence does temperature have on material's hazards?

    <p>Temperature affects both the range of hazards and the countermeasures needed.</p> Signup and view all the answers

    What does the term 'supercool' refer to in the context of liquids?

    <p>The ability of certain liquids to remain in a liquid state below their freezing point without solidifying.</p> Signup and view all the answers

    What property determines whether an object will sink or float in a liquid?

    <p>Density of the object compared to the liquid</p> Signup and view all the answers

    Which of the following statements describes the effect of temperature on the density of a substance?

    <p>As matter gets colder, it becomes denser.</p> Signup and view all the answers

    Which cryogenic liquid when spilled has a significant reaction hazard, especially with organic materials?

    <p>Liquid chlorine</p> Signup and view all the answers

    What is a possible consequence of the rapid expansion of liquefied gases?

    <p>Buildup of extremely high pressure leading to failure</p> Signup and view all the answers

    What defines a hydrophobic element in terms of its interaction with water?

    <p>It repels water.</p> Signup and view all the answers

    What defines a flammable liquid according to the NFPA?

    <p>A liquid with a flash point below 100°F (38°C)</p> Signup and view all the answers

    How is flash point defined in relation to continuous burning?

    <p>The temperature at which vapors ignite but do not sustain combustion</p> Signup and view all the answers

    Which temperature measurement scale is commonly used in scientific settings?

    <p>Kelvin and Rankine</p> Signup and view all the answers

    What generally happens to the flow of a liquid as its temperature increases?

    <p>It becomes thinner and more fluid</p> Signup and view all the answers

    Which statement about molecular weight and flash point is correct?

    <p>Higher molecular weight typically corresponds to a higher flash point</p> Signup and view all the answers

    What is the primary risk associated with the inhalation of materials?

    <p>It can cause injury or death</p> Signup and view all the answers

    What do volatile substances produce that are responsible for combustion?

    <p>Vapors from the liquid</p> Signup and view all the answers

    What characteristic of liquid is measured by its viscosity?

    <p>The ease with which it can flow</p> Signup and view all the answers

    What is generally the expected condition of vapors from a liquid with a high molecular weight?

    <p>They are heavier than air</p> Signup and view all the answers

    Why might unexpected odors indicate a potential hazard?

    <p>They may warn that a substance has escaped from its container</p> Signup and view all the answers

    What distinguishes flammable liquids from combustible liquids based on flash points?

    <p>Flammable liquids have a flash point below 100°F.</p> Signup and view all the answers

    Which statement about temperature measurement scales is accurate?

    <p>Celsius and Fahrenheit scales are common for everyday temperature measurements.</p> Signup and view all the answers

    How does molecular weight generally affect the flash point of a substance?

    <p>In general, the lower the molecular weight, the lower the flash point.</p> Signup and view all the answers

    In the context of heat and molecular movement, what occurs when an object is heated?

    <p>The movement of molecules in the object increases.</p> Signup and view all the answers

    What is true regarding the states of matter in relation to temperature and heat?

    <p>Matter can change phases when heat is added or removed.</p> Signup and view all the answers

    What is the primary substance that burns when dealing with a flammable liquid?

    <p>Only the vapors produced by the liquid burn.</p> Signup and view all the answers

    Which of the following is a characteristic of a liquid with heavy vapors?

    <p>If on the ground, the vapors will sink.</p> Signup and view all the answers

    What does an average color listing on an SDS indicate?

    <p>The average color may not accurately reflect the actual product in shipment.</p> Signup and view all the answers

    Which factor is not mentioned as affecting the state of a product?

    <p>Color intensity</p> Signup and view all the answers

    What occurs to a material at its melting point?

    <p>It changes from a solid to a liquid.</p> Signup and view all the answers

    What is the relationship between boiling point and vapor content of a material?

    <p>Higher boiling point correlates with lower vapor content.</p> Signup and view all the answers

    Which statement describes autoignition temperature?

    <p>It is the temperature at which a substance will spontaneously ignite in air.</p> Signup and view all the answers

    Which process is described as the conversion of a vapor into a liquid?

    <p>Condensation</p> Signup and view all the answers

    What does volatility refer to in materials?

    <p>The ease with which a material changes to a vapor.</p> Signup and view all the answers

    Which of the following defines critical temperature?

    <p>The temperature beyond which a gas cannot be liquefied, regardless of pressure.</p> Signup and view all the answers

    What is sublimation in the context of phases of matter?

    <p>Converting directly from solid to vapor without becoming liquid.</p> Signup and view all the answers

    What is the relationship between temperature and pressure described in the content?

    <p>Temperature and pressure are directly proportional to one another.</p> Signup and view all the answers

    What defines the maximum safe storage temperature (MSST) for a product?

    <p>The highest allowable temperature for safe storage, below the self-accelerating decomposition temperature.</p> Signup and view all the answers

    Which of these statements best describes polymerization?

    <p>A reaction in which monomers form larger molecules called polymers.</p> Signup and view all the answers

    What happens as temperature of a material increases based on molecular behavior?

    <p>Molecular speed and kinetic energy increase.</p> Signup and view all the answers

    Which of the following statements about flash points is true?

    <p>Flash points can indicate the flammability level of a substance.</p> Signup and view all the answers

    How does molecular weight generally influence the flash point of a product?

    <p>Higher molecular weight typically correlates with higher flash points.</p> Signup and view all the answers

    What is the primary factor affecting a liquid's viscosity?

    <p>Temperature has a significant influence on the viscosity of a liquid.</p> Signup and view all the answers

    Why should odors not be used to define safe areas around flammable liquids?

    <p>Inhalation of materials can occur without any odor being present.</p> Signup and view all the answers

    What is the correct definition of a flammable liquid according to U.S.DOT?

    <p>A liquid that can ignite below 141°F.</p> Signup and view all the answers

    Which statement accurately reflects the concept of flash point in flammable liquids?

    <p>It is the lowest temperature at which a liquid can form an ignitable mixture in air.</p> Signup and view all the answers

    How does molecular weight generally influence the volatility of a substance?

    <p>Lower molecular weight generally leads to lower volatility.</p> Signup and view all the answers

    What implication does a significant color variation listed on an SDS have?

    <p>It indicates possible contamination or impurities in the product.</p> Signup and view all the answers

    Which temperature measurement scales are less common in everyday use compared to Celsius and Fahrenheit?

    <p>Kelvin and Rankine</p> Signup and view all the answers

    What is the principle behind the flammability of liquid substances?

    <p>The liquid does not burn, but its vapors catch fire.</p> Signup and view all the answers

    What occurs to the molecular movement in a substance as heat is applied?

    <p>Molecular movement increases, leading to a change in physical properties.</p> Signup and view all the answers

    How does polarity affect the physical state of a material?

    <p>It leads to decreased molecular distances due to intermolecular attractions.</p> Signup and view all the answers

    What is the relationship between temperature and the state of matter based on heating?

    <p>Temperature changes can cause matter to change states depending on heat application.</p> Signup and view all the answers

    What happens to vapors when they cool down, despite being initially hot?

    <p>They can sink if not dispersed.</p> Signup and view all the answers

    Which characteristic is true of most materials in relation to air?

    <p>They generally have a molecular weight greater than 29.</p> Signup and view all the answers

    In terms of odor, what indicates a potential leak from a substance's container?

    <p>An unexpected odor.</p> Signup and view all the answers

    What is the key relationship between temperature and the viscosity of liquids?

    <p>Higher temperature typically decreases viscosity.</p> Signup and view all the answers

    How does the molecular weight of hydrogen fluoride (HF) compare to its vapor density?

    <p>Its molecular weight is less than its vapor density.</p> Signup and view all the answers

    What does a description such as 'water white' on a Safety Data Sheet (SDS) signify?

    <p>The material is clear and colorless.</p> Signup and view all the answers

    What is typically true about cold vapors in terms of their density and behavior?

    <p>They are denser and tend to rise when they warm.</p> Signup and view all the answers

    Which statement is correct regarding the appearance of substances as described on an SDS?

    <p>It can vary significantly indicating potential hazards.</p> Signup and view all the answers

    Why is it cautioned against relying solely on odor to define safe areas?

    <p>Inhalation of materials can cause injury or death.</p> Signup and view all the answers

    What hazard arises from the vaporization of liquid gases that can lead to asphyxiation?

    <p>Displacement of oxygen in the air</p> Signup and view all the answers

    Why can extreme cold from cryogenic liquids lead to structural failures in metals?

    <p>They can become brittle, losing structural integrity</p> Signup and view all the answers

    What characteristic of liquid oxygen poses a significant explosive risk when it contacts certain materials?

    <p>It forms a powerful explosive with asphalt</p> Signup and view all the answers

    What is a key danger associated with the rapid expansion of liquefied gases?

    <p>Buildup of extremely high pressure leading to violent failure</p> Signup and view all the answers

    What type of materials absorb water, in contrast to hydrophobic elements?

    <p>Hydrophilic materials</p> Signup and view all the answers

    Which physical property measures how heavy a unit volume of a substance is?

    <p>Density</p> Signup and view all the answers

    How does temperature generally affect the density of substances?

    <p>Usually denser as matter gets colder</p> Signup and view all the answers

    What is the nature of metals when exposed to the extreme cold of cryogenic liquids?

    <p>They lose tensile strength thereby failing under pressure</p> Signup and view all the answers

    What condition increases the risk of ignition when certain pressurized gases are released?

    <p>Generation of large static-electric charges</p> Signup and view all the answers

    What effect can the presence of liquids like chlorine have in organic material spills?

    <p>They react violently, creating a fire hazard</p> Signup and view all the answers

    What occurs to the specific gravity of a material when its temperature increases?

    <p>It decreases due to the expansion of the material.</p> Signup and view all the answers

    Which of the following accurately describes water's characteristics in terms of density and specific gravity?

    <p>Water has a density of 62.4 lb/ft³ and a specific gravity of 1.</p> Signup and view all the answers

    How is vapor density determined for a gas?

    <p>By determining the ratio of its density to the density of air.</p> Signup and view all the answers

    What happens to the weight by volume of a material as its temperature increases?

    <p>It decreases because the density of the material decreases.</p> Signup and view all the answers

    If a gas has a vapor density greater than 1, what can it be concluded about its behavior in air?

    <p>It will sink and may accumulate in lower areas.</p> Signup and view all the answers

    What measurement does the NIOSH define as the relative gas density referenced to air?

    <p>It signifies the relative density of gases compared to air.</p> Signup and view all the answers

    Which unit conversion is correct for changing grams per milliliter to pounds per gallon?

    <p>Multiply g/ml by 8.34.</p> Signup and view all the answers

    What can be inferred if a material has a specific gravity equal to 1?

    <p>It has the same density as water.</p> Signup and view all the answers

    Which factor can affect the specific gravity reading of a material?

    <p>The temperature of the material.</p> Signup and view all the answers

    What does a vapor density of less than 1 signify for a substance?

    <p>The substance is lighter than air and will rise.</p> Signup and view all the answers

    What occurs to most materials when they are cooled?

    <p>They contract</p> Signup and view all the answers

    What is the process called when a liquid changes to vapor at temperatures below its boiling point?

    <p>Evaporation</p> Signup and view all the answers

    At what pressure is the standard boiling point of a liquid defined?

    <p>1 atmosphere (1 bar)</p> Signup and view all the answers

    What differentiates the boiling point from the melting point of a substance?

    <p>Boiling point requires equal vapor pressure to atmospheric pressure</p> Signup and view all the answers

    What factor can cause a liquid to supercool?

    <p>Presence of contaminants</p> Signup and view all the answers

    What is the key characteristic of materials at their critical point?

    <p>They have equal densities as liquid and gas</p> Signup and view all the answers

    What commonly happens to water when it freezes?

    <p>It expands and can rupture containers</p> Signup and view all the answers

    Which condition typically prevents a substance from melting at its melting point?

    <p>Presence of impurities</p> Signup and view all the answers

    What does a specific gravity less than 1 indicate about a substance's behavior in water?

    <p>It will float on water.</p> Signup and view all the answers

    How is vapor density defined in relation to air?

    <p>It compares the density of a gas to the density of air, which is equal to 1.</p> Signup and view all the answers

    What is the impact of increasing temperature on the density of a material?

    <p>It decreases density because materials expand at higher temperatures.</p> Signup and view all the answers

    What unit conversion is necessary to find the weight of a substance in pounds per gallon from grams per milliliter?

    <p>Multiply by 8.34.</p> Signup and view all the answers

    What does the NIOSH RgasD measurement represent?

    <p>The ratio of gas density to the density of air at the same temperature.</p> Signup and view all the answers

    What term describes the ability of a material to readily transition from a liquid to a vapor?

    <p>Volatility</p> Signup and view all the answers

    Which of the following temperatures indicates that a gas cannot be liquefied regardless of how much pressure is applied?

    <p>Critical Temperature</p> Signup and view all the answers

    Which process allows a solid to transform directly into a vapor without passing through a liquid state?

    <p>Sublimation</p> Signup and view all the answers

    What describes the temperature above which the decomposition of an unstable substance continues unimpeded?

    <p>SADT</p> Signup and view all the answers

    How does the evaporation rate change with temperature variations?

    <p>It increases as temperature increases.</p> Signup and view all the answers

    What type of reaction occurs during polymerization?

    <p>Combination of small molecules</p> Signup and view all the answers

    Which relationship accurately describes the effect of temperature on gas pressure?

    <p>As temperature increases, pressure increases.</p> Signup and view all the answers

    What is the significance of critical pressure in relation to critical temperature?

    <p>It is the pressure needed to liquefy a gas at its critical temperature.</p> Signup and view all the answers

    What typically happens to vapors produced when a liquid is cooled below its boiling point?

    <p>They begin to condense back into a liquid.</p> Signup and view all the answers

    Which of these describes a consequence of reaching a critical point in chemical reactions?

    <p>The reaction cannot be stopped until completion.</p> Signup and view all the answers

    What is a possible risk associated with exposure to cryogenic liquids or gases?

    <p>Potential for severe frostbite and body tissue damage</p> Signup and view all the answers

    Which phenomenon can occur as a result of rapid expansion of liquefied gases?

    <p>Buildup of high pressure leading to violent failure</p> Signup and view all the answers

    How can liquid oxygen react with materials, and what is a possible outcome of that reaction?

    <p>It can create a powerful, sensitive explosive with asphalt</p> Signup and view all the answers

    What happens to metals when exposed to cryogenic temperatures?

    <p>They may become brittle, increasing risk of failure</p> Signup and view all the answers

    What characteristic distinguishes hydrophobic materials from hydrophilic materials?

    <p>Hydrophobic materials repel water</p> Signup and view all the answers

    Which physical property of a material measures how heavy a unit volume is?

    <p>Density</p> Signup and view all the answers

    What effect does temperature generally have on the density of a substance?

    <p>Density usually decreases as matter gets warmer</p> Signup and view all the answers

    What is a common charge condition that some pressurized gases may develop upon release?

    <p>They generate large static-electric charges</p> Signup and view all the answers

    How should the density of a substance affect its behavior in liquid?

    <p>Density comparison determines if an object will float or sink</p> Signup and view all the answers

    Which cryogenic liquid poses a unique hazard due to reactivity with organic materials?

    <p>Liquid oxygen</p> Signup and view all the answers

    What is a unique characteristic of gases compared to solids and liquids in terms of their volume?

    <p>They do not have a specific volume.</p> Signup and view all the answers

    Which of the following describes how solids differ from liquids in terms of molecular behavior?

    <p>Solids have a definitive shape and volume.</p> Signup and view all the answers

    Which challenge is associated with handling hazardous materials in their gaseous form?

    <p>They can be toxic, corrosive, or flammable.</p> Signup and view all the answers

    What occurs when gases are cooled, according to the properties of matter?

    <p>They may take liquid form.</p> Signup and view all the answers

    How does the behavior of gas molecules compare to that of solid molecules?

    <p>Gas molecules move with a great deal of energy.</p> Signup and view all the answers

    What happens to a piece of wood when it is reduced to sawdust concerning air movement?

    <p>It increases its surface area, becoming airborne more easily.</p> Signup and view all the answers

    Which physical property is not typical of liquids compared to solids?

    <p>They have a definitive shape.</p> Signup and view all the answers

    What characterizes the least dense state of matter?

    <p>Gases are the least dense and can be compressed.</p> Signup and view all the answers

    Why might emergency responders be at higher risk when dealing with gases?

    <p>They can be difficult to contain and may be toxic.</p> Signup and view all the answers

    Study Notes

    Changes of State

    • A change of state or phase involves a change in the physical form of a substance, such as solid to liquid or liquid to gas.
    • These changes always involve a change in heat.
    • Matter contracts when it gets cold and expands when it gets hot, but water expands when it freezes.
    • The temperature at which a solid turns into a liquid is called its melting point.
    • The freezing point is the temperature at which a liquid solidifies or crystallizes.
    • The boiling point is the temperature at which the vapor pressure of a liquid equals the atmospheric pressure.
    • Evaporation is a surface phenomenon where molecules near the liquid's edge escape into the atmosphere as vapor.
    • The rate of evaporation is affected by temperature, with higher temperatures resulting in faster evaporation.
    • Sublimation is the transformation of a solid directly into a vapor without becoming a liquid.
    • Dry ice (solid carbon dioxide) sublimates, as does iodine, which can travel through the air until it condenses in a cool spot.

    Critical Points

    • Critical points are thresholds in temperature and pressure that can initiate chemical reactions that cannot be stopped until completion.
    • The critical temperature is the minimum temperature above which a gas cannot be liquefied, regardless of pressure.
    • The critical pressure is the pressure needed to liquefy a gas at its critical temperature.
    • The autoignition temperature is the lowest temperature at which a substance will ignite without an ignition source.
    • The self-accelerating decomposition temperature (SADT) is the temperature above which decomposition continues unimpeded, regardless of external temperature.
    • The maximum safe storage temperature (MSST) is the maximum safe temperature for storage, well below the substance's SADT.
    • Polymerization is a chemical reaction where monomers combine to form polymers.

    Temperature & Pressure

    • As temperature increases, so does pressure.
    • The speed of molecules increases with temperature, increasing the force on the container walls, leading to higher pressure.

    Understanding Properties

    • Understanding physical properties helps hazmat technicians identify the hazards of a substance.
    • A low boiling point generally indicates a low flash point, leading to a high vapor pressure.
    • A high boiling point and flash point typically indicate a low vapor pressure.
    • SDSs provide information on a material's appearance, including color. However, color may not always be a reliable indicator of purity.

    Temperature Measurement

    • Common temperature scales include Celsius (°C) and Fahrenheit (°F).
    • Kelvin (K) and Rankine (°Ra) are also used in scientific contexts.
    • Increasing heat increases the movement of molecules within an object.

    Flash Point

    • The flash point is the lowest temperature at which a liquid can form an ignitable mixture in air near the liquid's surface but won't sustain continuous burning.
    • NFPA defines flammable liquids as having flash points below 100°F (38°C) and combustible liquids as having flash points above 100°F (38°C).
    • US DOT defines flammable liquids as having flash points below 141°F (60°C).
    • A lower flash point indicates higher flammability.
    • Liquids themselves don't burn; the vapors produced from them do.
    • The lower the molecular weight of a product, generally the lower its flash point.
    • Vapors from liquids are typically heavier than air.

    Viscosity

    • Viscosity measures the internal friction of a liquid at a given temperature.
    • It determines how easily a product flows.
    • Liquids typically become thinner (more fluid) as they get hotter and thicker (less fluid) as they get colder.

    Odor

    • Odor is a characteristic scent produced by a chemical.
    • Some chemicals have little or no odor, while others have strong, distinctive odors.
    • A sudden or unexpected odor can indicate a chemical release.
    • Odor reports from callers or victims can provide initial information, but never rely on odor alone to determine safety.

    Appearance

    • Materials have characteristic appearances based on their composition.
    • Vapors from liquids or gases can displace oxygen, causing asphyxiation.
    • Cryogenic liquids can cause frostbite and can make metals brittle.
    • Rapid expansion of liquefied gases or cryogenic liquids can lead to high pressure and equipment failure (BLEVE).
    • Gases may generate static electricity when released, potentially igniting flammable atmospheres.
    • Cryogenic liquids and gases have reactive hazards different from their ambient temperature counterparts.

    Water Reactions

    • Anhydrous means "dry" or without water.
    • Materials can be hydrophobic (water-repelling) or hydrophilic (water-absorbing).

    Other Physical Properties

    • Density is the mass of a substance per unit volume.
    • Density generally decreases with increasing temperature.
    • Density determines if something will sink or float in a liquid.
    • Specific gravity compares the density of a substance to the density of water.
    • Vapor density compares the density of a substance's vapor to air.
    • Viscosity measures the resistance to flow.
    • Odor is the smell produced by a substance.
    • Appearance includes physical characteristics like color, state, and form.

    Physical Properties

    • An SDS will normally include a description of a substance's appearance, such as its physical state and color.
    • The color listed on the SDS often represents an average value, as the actual color can vary depending on the specific batch shipped.
    • Significant differences in color can indicate contamination or impurities, which may pose their own hazards.
    • Temperature can influence the physical properties of a substance.
    • Common temperature scales include Celsius (°C) and Fahrenheit (°F).
    • The movement of molecules within a substance increases with heat.

    Flammability and Flash Point

    • Flammable liquids have a flash point, which is the minimum temperature required for the substance to form an ignitable mixture with air.
    • NFPA defines flammable liquids as having a flash point below 100°F (38°C), while combustible liquids have a flash point above 100°F (38°C).
    • U.S. DOT classifies flammable liquids as those with a flash point below 141°F (60°C).
    • A lower flash point indicates higher flammability.
    • The vapors produced by liquids actually burn, not the liquids themselves.
    • Molecular weight is a significant factor affecting the flash point: lower molecular weight generally correlates with a lower flash point.
    • Vapors from liquid products are often heavier than air.

    State Changes and Cryogenic Liquids

    • Matter can transition between solid, liquid, and gas states.
    • Vaporization of liquids or gas release from pressurized cylinders can displace oxygen, leading to asphyxiation.
    • Exposure to cryogenic liquids can cause severe frostbite, tissue damage, and embrittlement of metals.
    • Rapid expansion of cryogenic liquids or liquified gases can generate high pressure and cause violent container failure (similar to a BLEVE).
    • Some pressurized gases can create large static-electric charges during release, posing a risk of igniting flammable atmospheres.
    • Cryogenic liquids can possess unique reactive hazards beyond those associated with the same substances at ambient temperatures.
    • Liquid oxygen can form a sensitive contact explosive with asphalt, potentially detonated by a footstep.
    • Liquid chlorine reacts violently with most organic materials, creating extreme fire danger in the event of a spill.

    Water Reactions

    • "Anhydrous" denotes a material without water.
    • Hydrophobic elements repel water, while hydrophilic elements and materials absorb water.

    Physical Properties and Measurements

    • Density measures a substance's weight per unit volume.
    • Density changes with temperature, becoming denser with colder temperatures.
    • Comparing densities helps determine if an object will sink or float in a liquid.
    • Density units include grams per milliliter (g/ml) or pounds per gallon (lb/gal).
    • Specific gravity is a ratio of a substance's density to the density of water (which has a specific gravity of 1).
    • Materials with a specific gravity less than 1 float in water, while those greater than 1 sink.
    • Vapor density compares the density of a gas or vapor to air (density of 1).
    • Gases with a vapor density less than 1 are lighter than air and will rise, while those greater than 1 are heavier than air and will sink.
    • It's possible to estimate vapor density by dividing the molecular weight of a substance by the average molecular weight of air (29).
    • Viscosity measures a liquid's internal friction at a specific temperature.
    • Higher viscosity indicates thicker and less fluid substances.
    • Odor is subjective and can alert responders to potential releases.
    • Always use detection and monitoring equipment to assess atmosphere safety, never rely solely on odor.

    Appearance

    • Elements, compounds, and mixtures have a characteristic appearance based on their composition.
    • An SDS will usually include a description of a material's appearance.

    Matter and Its States

    • Chemical composition remains constant during changes in state.
    • Changes in state require heat transfer: heat is added during melting and boiling, and heat is removed during freezing and condensation.

    Temperature and Its Impact

    • Materials generally contract when cold and expand when hot, but exceptions occur (e.g., water expanding when freezing).
    • Melting point is the critical temperature at which a solid turns into a liquid.
    • Freezing point is similar to or the same as the melting point, but some materials can supercool.
    • Boiling point is the temperature at which a liquid's vapor pressure equals atmospheric pressure.
    • Evaporation is a surface phenomenon where molecules escape into the atmosphere as vapor.
    • Evaporation rates are influenced by temperature: higher temperatures lead to faster evaporation.

    Sublimation

    • Sublimation is the direct conversion of a solid to a vapor without a liquid phase.
    • Examples include dry ice (solid carbon dioxide) and iodine.
    • Sublimation can lead to the movement of hazardous materials due to the condensation of vapors in cooler areas.

    Critical Points

    • Critical points are thresholds beyond which chemical reactions cannot be stopped until completion.
    • Critical temperature is the minimum temperature above which a gas cannot be liquefied, regardless of pressure.
    • Critical pressure is the pressure required to liquefy a gas at its critical temperature.
    • Autoignition temperature is the lowest temperature at which a substance ignites in air without an external ignition source.
    • Self-accelerating decomposition temperature (SADT) is the temperature at which an unstable substance decomposes uncontrollably.
    • Maximum safe storage temperature (MSST) is the maximum temperature for safe storage, lower than the SADT
    • Polymerization is a chemical reaction where monomers combine to form larger polymer molecules.

    Temperature and Pressure

    • Temperature and pressure are directly proportional: Increased temperature results in increased molecular speed and higher pressure.

    Physical Properties

    • Knowledge of physical properties aids hazmat technicians in understanding the product involved in an incident.
    • Materials with low boiling points typically have low flash points and high vapor pressure and content.
    • Materials with high boiling points and flash points generally have low vapor pressure and content.

    States of Matter

    • Solids:
      • Have a fixed volume and shape.
      • Can become airborne in a fine, powdered form.
    • Liquids:
      • Have a fixed volume but take the shape of their container.
      • Molecules can flow freely.
      • May be more difficult to contain than solids due to their mobility and potential for vaporization.
    • Gases:
      • Have no fixed volume or shape and will expand to fill any container.
      • Molecules possess high energy and mobility.
      • Are the least dense state of matter and are compressible.
      • Cooling can cause gases to condense into liquids.
      • Pose the greatest risk to emergency responders due to their volatility and the potential for inhalation exposure.
      • May have a variety of hazards including toxicity, corrosivity, flammability, high pressure, extreme cold and large expansion ratios.

    Atmospheric Pressure

    • Atmospheres (atm) are commonly used as a unit of pressure in the US.
    • Vaporizing liquids or gases released from pressurized cylinders can displace oxygen, leading to asphyxiation.

    Cryogenic Liquids and Gases

    • Cryogenics can cause extreme cold, leading to:
      • Frostbite and tissue damage.
      • Brittleness of metals, resulting in container or structural failure.
      • Rapid expansion with high pressure buildup, potentially causing a BLEVE (Boiling Liquid Expanding Vapor Explosion).
      • Static electric charges upon release, posing an ignition risk for flammable atmospheres.
      • Unique reaction hazards, such as the violent reaction between liquid oxygen and asphalt or liquid chlorine with organic materials.

    Water Reactions

    • Anhydrous implies "dry" or without water.
    • Hydrophobic materials repel water.
    • Hydrophilic materials absorb water.

    Additional Physical Properties

    • Density: A measure of mass per unit volume.
      • Densities change with temperature: colder matter is denser.
      • Helps determine if a substance will float or sink in a liquid.
      • Usually expressed in grams per milliliter (g/ml) or pounds per gallon (lb/gal).
    • Specific Gravity: The ratio of a substance's density to the density of water.
      • Water has a specific gravity of 1.
      • Substances with specific gravity less than 1 float on water, while substances with specific gravity greater than 1 sink.
    • Vapor Density: The ratio of a gas or vapor's density to the density of air (air = 1).
      • Gases with a vapor density less than 1 are lighter than air and will rise.
      • Gases with a vapor density greater than 1 are heavier than air and will sink.
      • Similar to the Compressed Gas Association (CGA) specific gravity and NIOSH RgasD (relative gas density) measurements.
    • Viscosity: A liquid's resistance to flow.
    • Odor: The smell of a substance.
    • Appearance: The visual characteristics of a substance.

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    Test your knowledge on changes of state in matter, including the transition from solid to liquid, liquid to gas, and other related processes. Explore concepts like melting point, freezing point, boiling point, and evaporation. Understand how temperature affects these changes and discover sublimation.

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