Matter particulate level

Health effects attributed to sulfur oxides are likely due to exposure to sulfur dioxide, sulfate aerosols, and sulfur dioxide adsorbed onto particulate matter. Alone, sulfur dioxide will dissolve in the watery fluids of the upper respiratory system and be absorbed into the bloodstream. Sulfur dioxide reacts with other substances in the atmosphere to form sulfate aerosols. Since most sulfate aerosols are part of PMj 5, they may have an important role in the health impacts associated with fine particulates. However, sulfate aerosols can be transported long distances through the atmosphere before deposition actually occurs. Average sulfate aerosol concentrations are about 40% of average fine particulate levels in regions where fuels with high sulfur content are commonly used. Sulfur dioxide adsorbed on particles can be carried deep into the pulmonary system. Therefore, reducing concentrations of particulate matter may also reduce the health impacts of sulfur dioxide. Acid aerosols affect respiratory and sensory functions. 

Burning fossil fuels can release air pollutants such as carbon dioxide, sulfur oxides, nitrogen oxides, ozone, and particulate matter. Sulfur and nitrogen oxides contribute to acid rain ozone is a component of urban smog, and particulate matter affects respiratory health. In fact, several studies have documented a disturbing correlation between suspended particulate levels and human mortality. It is estimated that air pollution may help cause 500,000 premature deaths and millions of new respiratory illnesses each year. 

The three representations that are referred to in this study are (1) macroscopic representations that describe the bulk observable properties of matter, for example, heat energy, pH and colour changes, and the formation of gases and precipitates, (2) submicroscopic (or molecular) representations that provide explanations at the particulate level in which matter is described as being composed of atoms, molecules and ions, and (3) symbolic (or iconic) representations that involve the use of chemical symbols, formulas and equations, as well as molecular structure drawings, models and computer simulations that symbolise matter (Andersson, 1986 Boo, 1998 Johnstone, 1991, 1993 Nakhleh Krajcik, 1994 Treagust Chittleborough, 2001). 

This test is to assess the efficacy of the vial/ampoule washer in reducing the particulate level in contaminated vials. Particulate matter to be determined in eight vials/ampoules, each spiked with approximately 500 particles of 40- im glass beads. A sample is to be taken from each individual needle at the end of vial/ampoule washing at set operational parameter of vial/ampoule washer and analyzed to determine the reduction in particulate level. The X ml vials/ampoules are to be washed according to the operational parameters described for each vial/ampoule size. The results are to be compared with negative and positive controls. The test results for each size of vial/ampoule are to be entered in Table 2. 

In addition, the Web can offer users animated representations of chemical phenomena and animations at the molecular and particulate levels. Animated representations can show molecular motion and connections among macroscopic, microscopic, and symbolic worlds. On a website, molecular-level views of motion can be shown as appropriate for the respective phases of matter. On paper, it is not possible to show such motion in progress. 

Most burns produce an abundance of particulate matter. Particulate matter at ground level is a health concern close to the fire and under the plume, although concentrations decline rapidly downwind from the fire. The greatest concern is the smaller or respirable particles that are 10 pm or less in size. Concentrations at ground level (1 m) can still be above normal health concern levels (150 pm/m ) as far downwind as 500 m from a small crude oil fire, such as from the amount of oil that could be contained in a 500-m long boom. 

Finally, particulate matter (PM), or the solid and liquid particles that are released into the atmosphere, comes from both the actual emissions of particulates and the reaction between atmospheric molecules and SO2 or NO. Particulate matter can be divided based on the size of the particle. Health effects include respiratory distress as well as cancer and permanent lung damage. Fine particulate matter (<2.5 microns in size, PM 2.5) is a major cause of reduced visibility, or haze, in many parts of the country. The EPA notes visibility in several of our nation s national parks and wilderness areas has been negatively affected by high particulate levels in the air. Particulate emissions that are not the result of other pollutants or natural causes come primarily from the industrial sector (EPA 1995). 

Figure 1.3 I Particulate level views of the solid, Uquid, and gas phases of matter. In a solid, the molecules maintain a regular ordered structure, so a sample maintains its size and shape. In a liquid, the molecules remain close to one another, but the ordered array breaks down. At the macroscopic level, this allows the Uquid to flow and take on the shape of its container. In the gas phase, the molecules are very widely separated, and move independently of one another. This allows the gas to fill the available volume of the container.

These air pollutants include particulate matter, ground-level ozone, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead, which are summarized in Table 10.13. 

Identify and explain the differences among observations of matter at the macroscopic, microscopic, and particulate levels. 

Learn It Now Performance goals tell you what you should be able to do after you study a section. Always focus your study on the goals. When you complete this section, you should know the differences among matter at the macroscopic microscopic, and particulate levels and you should be able to define the term model as it is used in this text. 

Chemists often think about matter that is too small to be seen even with the most powerful optical microscope. Usually, a chemist considers the behavior and transformations of molecules, extremely tiny particles that make up all matter. Thinking this way is thinking at the particulate level. One of the most valuable skills you will learn in this course is to think about particulate matter. 

Most of the time, chemists work with macroscopic samples in the laboratory, but they imagine what happens at the particulate level while they do so. Biologists frequently work with microscopic samples, but they also think about the particulate-level behavior of their samples to supplement their understanding of what they see through the microscope. By understanding and directing the behavior of particles, the chemist and biologist control the macroscopic behavior of matter. 

Since matter at the particulate level is too small to see, chemists use models to represent the particles. A model is a representation of something else. Chemists use models of atoms and molecules, tiny particulate-level entities, that are based on experimental data. We cannot see atoms and molecules directly, so we use data from experiments to infer what they would look like if they were much, much larger. We then construct physical models that match the data. 

Figure 2.1 Macroscopic, microscopic, and particulate matter. The particulate-level drawings are models of types of matter too small to see with the human eye or an optical microscope. Electron microscopes shine a beam of electrons through a sample in much... 

Figlire Z4 Macroscopic, particulate, and symbolic forms and representations of matter. Chemists frequently make mental transformations between visible macroscopic matter and models of the particulate-level molecules that make up the matter. Written symbols serve as simpler representations of the particulate-level models. 

All other substances have particulate-level behavior similar to that of water with respect to how they behave in and change among the three states of matter. Practice using your mental movie of molecules in different states of matter as you study the rest of this chapter. 

Representations of Matter Models and Symbols COAL 1 Identify and explain the differences among observations of matter at the macroscopic, microscopic, and particulate levels. COAL 2 Define the term model as it is used in chemistry to represent pieces of matter too small to be seen. 

Suggest a reason for studying matter at the particulate level, given that it is too small to be seen. 

You are familiar with the fact that ice—solid water—floats on liquid water. Why is this Ice is less dense than liquid water. What does this mean on the particulate level Considering the definition of density, a given volume of ice must have less mass than the same volume of liquid water. In other words, if all water molecules have the same mass and volume, whether liquid or solid, the molecules in liquid water must pack more closely together than molecules in ice. Figure 3.10 shows how solid water forms ice crystals with spaces between the molecules, whereas liquid molecules have fewer and smaller open spaces. So, at the particulate level, the density of a given pure substance in a given state of matter is a measure of how tightly packed the molecules are in that state. Water is an unusual substance, and the fact that its solid phase is less dense than its liquid phase is just one of many of its unusual properties. The solid phase is more dense than the liquid phase of almost all other substances (Fig. 3.11). 

In Section 2.1 we said that you would study chemistry at the particulate level. In other words, chemists are interested in the individual particles that make up a sample of matter. In Section 2.6 we identified atoms and molecules as two of these particles. To understand the amounts of substances in a chemical change, we must know the number of particles of the different substances in the reaction. That s not an easy number to find. Literally counting atoms and molecules is not practical. The number is extremely large. 

In Chapter 2 we stated that a chemical change occurs when the chemical identity of a substance is destroyed and a new substance forms. Particles of matter are literally changed. The number and type of atoms that make up molecules are the same before and after a chemical change, but the number and type of molecules changes. If we could observe matter at the particulate level, we would have a simple method for detecting chemical change. Of course, we cannot directly see what happens at the particulate level, so we must rely on indirect evidence of particulate-level rearrangements. 

Environment Canada has collected inhalable partides (<10 pm in diameter) in 15 Canadian cities since May 1984. Restdts for the period from May 1984 to December 1987 show that average inhalable particulate levels ranged fi om 17 pg/m in St. John s to 49 pg/m at a site in Montreal. Analysis has shown that the finest of the inhalable particles— those with a diameter less than about 2.5 pm— are different in origin and composition from the coarser particles in the 2.5- to 10-pm-diameter range. The coarse particles are mostly of natural origin (minerals from Earth s crust, sea salt, and plant material), whereas the fine particles consist of lead, sulfates, nitrates, carbon, and a variety of organic compoimds, mainly resulting from man-made pollution. At eastern Canadian sites, fine particulate matter accounted for more than 60 percent of the inhalable particles at sites in the Prairie provinces, the fine fraction was usually less than 40 percent of the inhalable particles. 

Phthalates in Air. Atmospheric levels of phthalates in general are very low. They vary, for DEHP, from nondetectable to 132 ng/m (50). The latter value, measured in 1977, is the concentration found in an urban area adsorbed on airborne particulate matter and hence the biological avaUabUity is uncertain. More recent measurements (52) in both industrial and remote areas of Sweden showed DEHP concentrations varying from 0.3 to 77 ng/m with a median value of 2 ng/m. ... 

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