1 ایمنی مواد شیمیایی خواص فیزیکی و شیمیایی مواد Physical and Chemical Propertiesدکتر مهدی جهانگیر بلورچیان دانشکده بهداشت دانشگاه علوم پزشکی گیلان 1390

2 خواص فیزیکی و شیمیایی موادوزن مولکولی حالت فیزیکی: جامد , مایع و گاز شکل فیزیکی رنگ بو اسیدیته حلالیت آب حلالیت در حلالهای آبی وزن مخصوص نسبت به آب (دانسیته ) فرمول شیمیایی دمای انفجار دمای خود آتشگیری نقطه اشتعال نقطه ذوب نقطه جوش فشار بخار

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5 خواص فیزیکی و شیمیایی موادنقطه ذوب: دمایی است كه در آن دما یك جسم شروع به ذوب شدن می ‏كند. نقطه جوش: دمایی است كه در آن دما یك جسم شروع به جوشیدن می ‏كند.

6 چگالي جرم يك حجم واحد از يك جسم را چگالي مي‌نامند.ارشميدس كشف كرد كه اگر جسمي را در آب فرو برند، مقداري از وزن آن كاسته مي‌شود. مقدار كاهش وزن مساوي با وزن آبي است كه جسم جاي آن را گرفته است. اين دانشمند تاجي را در آب فرو برد و آب جابجا شده را اندازه گرفت. بعد قطعه‌اي طلا كه وزنش مساوي تاج بود در آب فرو برد و آب جابجا شده را اندازه گرفت. آنگاه ديد كه تاج بيشتر از طلا آب را جابجا كرده است و فهميد كه تاج از طلاي خالص نيست. اما اگر يك قطعه نقره و يك قطعه طلا با حجم مساوي را درنظر بگيريم، مي‌توانيم بگوييم طلا سنگين‌تر است. جرمهايي كه حجم مساوي داشته باشند و از اجسام مختلف باشند، چگالي مختلف دارند. چون تاج از قطعه طلايي كه حجمش با آن مساوي بود، سبك‌تر بود لذا چگالي آن كمتر بود. واحد چگالي در سيستم متريك، گرم بر سانتي‌متر مكعب است.

7 چگالي براي اينكه چگالي‌ها را بصورت عدد درآوريم، بايد اجسامي را كه چگالي مختلف دارند با يكديگر مقايسه و مقياس اصلي را انتخاب كنيم. دانشمندان براي مايعات و جامدات، آب و براي گازها، هوا را مقياس اصلي قرار داده‌اند. يك سانتي‌متر مكعب آب، يك گرم جرم دارد. بنابراين چگالي آب در سيستم متريك، يك گرم بر سانتي‌متر است. نسبت چگالي‌ها به مقياس اصلي را با كلمه‌ي (( مخصوص )) نشان مي‌دهيم. نسبت چگالي يك جسم به چگالي مقياس اصلي، وزن مخصوص ناميده مي‌شود.   مثلاً چگالي طلا 3/19 گرم در سانتي‌مترمكعب است، يعني يك سانتي‌متر مكعب طلا جرمي معادل 3/19 گرم دارد. بنابراين طلا 3/19 برابر آب چگالي دارد يا وزن مخصوص طلا 3/19 است. ما مي‌توانيم چگالي هر يك از حالتهاي ماده يعني جامد و مايع و گاز را تعيين كنيم. ابتدا جرم آن و سپس حجم آن را معين مي‌كنيم، آنگاه جرم را به حجم تقسيم مي‌كنيم تا چگالي را بدست آوريم. جرم را مي‌توانيم با ترازو معين كنيم. ما مي‌توانيم حجم جامداتي را كه شكل منظم دارند محاسبه كنيم. براي تعيين حجم جامداتي كه شكل منظم ندارند، آنها را در آب فرو مي‌بريم و حجم آب جابجا شده را اندازه مي‌گيريم.

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11 چگالي مخلوط يا آلياژ چند جسم

12 چگالي مخلوط يا آلياژ چند جسم

13 نام ماده : اسيد سولفوريكH2SO4 كاربرد : اسيد سازي ـ خمير مالي ـ فرماسيون

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23 The physical properties of an object are defined traditionally in a Newtonian sense; the physical properties of an object may include, but are not limited to: absorption albedo area brittleness boiling point capacitance color concentration density dielectric ductility distribution efficacy electric charge electrical conductivity electrical impedance electric field electric potential emission flexibility flow rate fluidity frequency inductance Intrinsic impedance intensity irradiance length location luminance luster malleability magnetic field magnetic flux mass melting point moment momentum permeability Permittivity pressure radiance solubility specific heat resistivity reflectivity spin strength temperature tension thermal conductivity velocity viscosity volume wave impedance

24 Physical properties include:appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others. The three states of matter are: solid, liquid, and gas. The melting point and boiling point are related to changes of the state of matter. All matter may exist in any of three physical states of matter.

25 Physical Changes: A physical change takes place without any changes in molecular composition. The same element or compound is present before and after the change. The same molecule is present through out the changes. Physical changes are related to physical properties since some measurements require that changes be made. Melting Point: As solid matter is heated it eventually melts or changes into a liquid state at the melting point. Ice (a solid form of water) melts at 0 oC and changes to the liquid state. Carbon dioxide melts at -56.6oC Boiling Point: As the liquid matter is heated further it eventually boils or vaporizes into a gas at the boiling point. Liquid water boils and changes into a gas, usually called steam or water vapor at 100 oC. In all three states the same molecules of water (H2O) are present.

26 Examples of chemical propertiesReactivity Heat of combustion Enthalpy of formation Toxicity Chemical stability in a given environment Flammability Preferred oxidation state(s) Coordination number Capability to undergo a certain set of transformations, for example molecular dissociation, chemical combination, redox reactions under certain physical conditions in the presence of another chemical substance Preferred types of chemical bonds to form, for example metallic, ionic, covalent For example, hydrogen has the potential to ignite and explode given the right conditions. This is a chemical property. Zinc reacts with hydrochloric acid to produce hydrogen gas. This is a chemical property.

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29 Carbon dioxide boils at -78.5oCIn the graphic on the left a block of dry ice as a solid is changing to the gaseous state. The molecules of CO2 are present throughout.

30 Sublimation: Iodine has a relatively unique property in that it can change directly from a solid to a gaseous state without going through the liquid state. As the iodine is heated it undergoes a physical change to the gas state as shown in the graphic on the left. Iodine in the gas state is a beautiful violet color.

31 What are Chemical Properties and Changes?Chemical properties of matter describes its "potential" to undergo some chemical change or reaction by virtue of its composition. What elements, electrons, and bonding are present to give the potential for chemical change.  It is quite difficult to define a chemical property without using the word "change". Eventually you should be able to look at the formula of a compound and state some chemical property. At this time this is very difficult to do and you are not expected to be able to do it. For example hydrogen has the potential to ignite and explode given the right conditions. This is a chemical property. Metals in general have they chemical property of reacting with an acid. Zinc reacts with hydrochloric acid to produce hydrogen gas. This is a chemical property.

32 Chemical Changes or Reactions:Chemical change results in one or more substances of entirely different composition from the original substances. The elements and/or compounds at the start of the reaction are rearranged into new product compounds or elements. A CHEMICAL CHANGE alters the composition of the original matter. Different elements or compounds are present at the end of the chemical change. The atoms in compounds are rearranged to make new and different compounds. Magnesium reacts with oxygen from the air producing an extremely bright flame. This is a chemical change since magnesium oxide has completely different properties than magnesium metal shown on the left.   Safety:  Do not try this without supervision and DO NOT LOOK DIRECTLY AT THE LIGHT! The atoms are rearranged - diatomic oxygen molecules are split apart so that one oxygen atom combines with one magnesium atom.

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34 Oxidation of Iron - a chemical change:For example iron has the potential to rust given the right conditions. This is a chemical property. If iron does rust, this is a slow chemical change since rust is an iron oxide with different properties than iron metal. In the graphic on the left, iron or steel wool is burning in a fast reaction with oxygen as contrasted with the slow rusting of iron also with oxygen. In the element iron only atoms of iron are in contact with each other. In the element oxygen each oxygen is joined with one other to make a diatomic molecule. These atoms and molecules are rearranged so that two iron atoms combine with three atoms of oxygen to form a new compound.

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36 Alka Seltzer The reactions in both of the (left and lower) cases start when a solid tablet is dropped into water. The chemicals in dry solid form must dissolve in the water before a reaction may take place. In both cases gas bubbles are observed. This is an initial chemical reaction. A flaming or glowing splint is used to test for the identity of the gases by using their chemical properties. Reactions: Alka-Seltzer: (Baking soda or sodium bicarbonate) NaHCO3 + Citric acid ---> CO2 + H2O + Sodium Citrate QUES.: Define chemical property. Then use this definition to describe the behavior toward the flaming splint for carbon dioxide in the example on the left. Answer: A chemical property defines whether a chemical reaction will or will not take place. Because the flame goes out, this shows that the chemical property of carbon dioxide gas is that no combustion reaction can take place in its presence.

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38 Efferdent The reactions in both of the (left and upper) cases start when a solid tablet is dropped into water. The chemicals in dry solid form must dissolve in the water before a reaction may take place. In both cases gas bubbles are observed. A flaming or glowing splint is used to test for the identity of the gases. Reaction: Efferdent: (sodium perborate - a source of hydrogen peroxide) = H2O2 + catalyst ---> O2 + H2O QUES.: Define chemical property. Then use this definition to describe the difference in behavior toward the flaming splint for both gases in the above examples.

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40 Zinc and Iodine ReactionThe reaction in this case is between two elements, zinc metal and iodine. Both look sort of grayish in the photo. The reaction is started between the dry powders by adding a few drops of water. The reaction occurs as a combination reaction between the two elements to produce a single compound. During the reaction zinc metal gives two electrons to two iodine atoms to produce zinc +2 ions and iodide -1 ions. The reaction is: Zn metal + I2 ----> ZnI2 The reaction between the two elements to produce zinc iodide is very exothermic. Some of the unreacted iodine solid is heated to a gaseous iodine which is purple in color. QUES.: A molecule is only defined as the simplest part of a compound with two or more atoms. (True or False) QUES.: For an exothermic reaction, heat is given off in the process. (True or False) QUES.: The fact that unreacted iodine changes to gaseous iodine is a: chemical or physical change?

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42 Chemical and Physical propertiesExamples of physical properties are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density. Examples of chemical properties are: heat of combustion, reactivity with water, PH electromotive force.

43 Chemical and Physical propertiesPhysical properties: Properties that do not change the chemical nature of matter Chemical properties: Properties that do change the chemical nature of matter

44 Chemical and Physical propertiesChanges in Properties of Matter Physical property changes of matter do not produce a new substance and are typically described by the following: Color – every object has a color Odor – intensity of smell Density – mass divided by volume Luster – how shiny it is Ductility – ability to be drawn into thin wires Malleability – ability to be beaten into thin sheets Elasticity – ability to return to original shape Hardness – ability to be scratched Conductivity – allows energy flow, electricity or heat Insulator – resists flow of energy, electricity or heat Organic/Inorganic – was once alive or is alive/was never alive Chemical property changes of matter produces a new substance and can be typically described by the following: Color – change in color indicates a chemical change Temperature – change in temperature indicates a chemical change

45 Standard enthalpy of formationThe standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually K or 25 degrees Celsius). Its symbol is ΔHfO or ΔfHO. For example, the standard enthalpy of formation of carbon dioxide would be the enthalpy of the following reaction under the conditions above: C(s,graphite) + O2(g) → CO2(g) The standard enthalpy of formation is measured in units of energy per amount of substance. Most are defined in kilojoules per mole (kJ mol−1), but can also be measured in calories per mole, joules per mole or kilocalories per gram (any combination of these units conforming to the energy per mass or amount guideline). In physics the energy per particle is often expressed in electronvolts which corresponds to about 100 kJ mol−1. All elements in their standard states (oxygen gas, solid carbon in the form of graphite, etc.) have a standard enthalpy of formation of zero, as there is no change involved in their formation.

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47 Laboratory absorber. 1a): CO2 inlet; 1b): H2O inlet; 2): outlet; 3): absorption column; 4): packing

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49 The colors of the visible light spectrum[1] color wavelength interval frequency interval red ~ 700–635 nm ~ 430–480 THz orange ~ 635–590 nm ~ 480–510 THz yellow ~ 590–560 nm ~ 510–540 THz green ~ 560–490 nm ~ 540–610 THz blue ~ 490–450 nm ~ 610–670 THz violet ~ 450–400 nm ~ 670–750 THz

50 These glasses containing red dye demonstrate qualitative changes in concentration. The solutions on the left are more dilute, compared to the more concentrated solutions on the right

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52 Electronic Configuration IA VIIIB 1  H  IIA  Periodic Table of the Elements **  IIIB  IVB  VB  VIB  VIIB  He 2  Li Be  B  C  N  O  F  Ne 3  Na  Mg  IIIA  IVA  VA  VIA  VIIA  VIII  IB  IIB  Al  Si  P  S  Cl  Ar 4  K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5  Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 6 Cs  Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7  Fr Ra Ac Rf Db Sg Bh Hs Mt Uun Uuu Uub Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Metals Metalloid Nonmetals Liquids at 20 C Name Density(a) Electronic Configuration Heat of vap.(b) Atomic Number Melting Point Oxidation States Heat of fus.(b) Atomic Weight (c) Boiling Point Half Life (d) S. heat (b) No. Stable Isotopes Radio Isotopes (e) Decay Particle E.N.(f) I.P.(g) Bond Radius(h) Atomic Radius(h)

53 Electronic ConfigurationName Density(a) Electronic Configuration Heat of vap.(b) Atomic Number Melting Point Oxidation States Heat of fus.(b) Atomic Weight (c) Boiling Point Half Life (d) S. heat (b) No. Stable Isotopes Radio Isotopes (e) Decay Particle E.N.(f) I.P.(g) Bond Radius(h) Atomic Radius(h) (a) g/cm3 (b) kJ/mol (c) Atomic weight in ( ) = mass number of most stable isotope (d) Half life of most abundant radioactive isotope (e) Number of naturally occuring radioactive isotopes (f) Electronegativity (g) Ionization potential (volts) (h) Angstroms

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