...SCH4U – The Chemistry of Covalent Bonding Date_____________________ Orbital Hybridization One of the most influential chemistry books ever written was The Nature of the Chemical Bond by Linus Pauling (1901-1994). Published in 1939, Pauling was awarded the Nobel Prize in 1954. Pauling received a second Nobel Prize for peace in 1962. Pauling made tremendous contributions to the field of chemistry, and was an outspoken activist against war and nuclear weapons. If you consider the energy level diagram for carbon it presents a problem to the VB theory. If bonds are formed between orbitals that contain unpaired electrons, how many bonds does it appear carbon can form? | | 2 | | 1 | | Since Carbon only has 4 different 4 valence electrons, according to the Aufbau principle, the 2s orbital is filled first, and then the 2p sub shell has 2 orbitals with unpaired electrons. This suggests that Carbon can only form 2 bonds. However Carbon is clearly able to form 4 bonds, as evidenced by any carbon compound (e.g. methane, CH4). Linus Pauling suggested that carbon is able to create four unpaired orbitals by promoting one electron from the 2s orbital to the empty 2pz orbital. This hybridizes the one 2s and three 2p orbitals together. This configuration is called ‘sp3’. Like s and p orbitals, the ‘shape’ of sp3 orbitals can be defined by a probability density map of electron location around the nucleus. The shape of a sp3 orbital looks like this: Since carbon...
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...Jacinta Houng Comparing the Solubility of Chemicals in Water “Water is known as the “universal solvent” because so many different substances dissolve in it and we rely on this for many of our daily needs.” Introduction: Water is known as the ‘universal solvent’ as it is capable of dissolving a variety of different substances and dissolves more substances than any other liquid. However the ability to be soluble depends on a substances polarity and bonding. This then contributes to the various ways that different types of chemicals interact in water. Solubility is crucial to every living thing on earth as water can carry along valuable chemicals, minerals, and nutrients necessary for survival. In fact Water covers 70% of the Earths surface and composes 55-70% of the human body. Water is an excellent solvent due to its chemical composition and physical attributes. According to USGS (http://water.usgs.gov/edu/qa-solvent.html ) Water molecules have a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) has a negative charge. A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. This causes the molecule to have a slight electrical dipole moment where one end is slightly positive and the other is slightly negative. "Like dissolves like" is an expression used by chemists to help them remember how solvents work. The expression refers to...
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...Physical Properties Boiling point is less than 500 degrees Celsius Melting point is between 169.0 - 170.5 degrees Celsius Odorless and has a bitter taste A white crystalline powder Density is at 1.293 g/cm^3 State at room temperature= solid Soluble in organic solvents like methanol and ethanol Not very soluble in water and ethene Acetaminophen (Tylenol) C8H9NO2 Chemical Properties IUPAC: N-(4-hydroxyphenyl)acetamide Common Names: Paracetamol, Tylenol, Panadol, Tempera, APAP Organic Family/ Functional Group Biological Importance Primary organic family: aromatics Functional groups: alcohols (OOH) and amide (OCONHO) Taking too much acetaminophen can lead to liver damage/failure or death FDA recommends daily maximum of 4,000 mg for adults; overdoses of this painkiller are some of most common poisonings Sources and Abundance Manufactured by Ortho McNeil Pharmaceuticals Inc., G and W Laboratories Inc., etc. Packaged by McNeil Laboratories, CVS Pharmacy, Walgreen Co., Interesting Facts Acetaminophen is the most popular pain relief medication used in the U.S. and around the world Accounts for over 100,000 calls to poison centers, 60,000 ER visits, hundreds of deaths annually in the U.S. In 1982, seven deaths occurred, known as Chicago Tylenol Murders, as result of taking Extra-Strength Tylenol caplets laced with cyanide Origin/Discovery In 1899, Karl Morner of Germany, discovered Acetanilide became Acetaminophen when the body ...
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...CHROMATOGRAPHY Chromatography (from Greek word Chroma means “color” and Graphein means “to write”) is the collective term used for the separation of the mixture. The mixture is dissolved in a fluid called the mobile phase, which carries it to another material known as the stationary phase. The separation is based on the speed of different constituents of the mixture and on the differential partition of the mobile and the stationary phase (web link7). Distribution or partition coefficient is the basis of chromatography which describes a way in which constituents of a mixture distributes between two immiscible phases. For two such phases A and B, the value for this coefficient is a constant at a given temperature and is given by the expression (36): Kd = Concentration in phase A Concentration in phase B COLUMN CHROMATOGRAPHY For separations of solid and liquids, column chromatography is one of the most important techniques. It is a solid liquid separation technique in which the stationary phase is solid and the mobile phase is liquid. It is based on the principle of differential adsorption of the substance by adsorbent (web link 8). The stationary phase is packed into a glass or metal column and mixture of analytes are then applied, the mobile phase (eluent) is passed through the column either by use of a pumping system or applied gas pressure. The stationary phase is either coated onto discrete small particles (the matrix)...
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...CHEMICAL BONDS Chemical Bonds I. Introduction Chemical compounds are formed by the joining of two or more atoms. A stable compound occurs when the total energy of the combination has lower energy than the separated atoms. The bound state implies a net attractive force between the atoms called a chemical bond. The two extreme cases of chemical bonds are the covalent bonds and ionic bonds. Covalent bonds are bonds in which one or more pairs of electrons are shared by two atoms. Covalent bonds, in which the sharing of the electron pair is unequal, with the electrons spending more time around the more non-metallic atom, are called polar covalent bonds. In such a bond there is a charge separation with one atom being slightly more positive and the other more negative, i.e., the bond will produce a dipole moment. On the other hand, Ionic bonds are bonds in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other. In the extreme case where one or more atoms lose electrons and other atoms gain them in order to produce a noble gas electron configuration, the bond is called an ionic bond. Covalent bonding is a form of chemical bonding between two non-metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds. Ionic bond, also known as electrovalent bond is a type of bond formed from the electrostatic attraction between oppositely charged...
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...Polarity Management of Cost and Quality Dustin Klinger Kaplan University Polarity Management of Cost and Quality Polarities are interdependent pairs that support a common purpose yet tend to be contradictory of one other (Polarity Partnerships, para. 1). Some examples of polarities include: stability and change, individual and team, long and short term, autocratic and participatory and my topic, cost and quality. Any of these pairs are known to counter the other. In my case, it is important to note that when quality improves, cost generally increases and vice versa. Throughout this paper I will discuss managerial approaches to utilize these two concepts to your advantage without ever overlooking either of them. It is important to embrace the fact that there are polarities everywhere we turn and instead of trying to fight against them, we should develop their concepts to make us more complete. Larry Hirschhorn has argued that in order for managers to become proficient in managing polarities, they must develop a set of “rules of thumb” for when they encounter different circumstances. They establish these rules with the hopes of somewhat standardizing their way of thinking as well as how to allocate resources for each instance. The guidelines are generally developed to recognize patterns and opportunities. Hirschhorn recommends managers create a 2 x 2 table to help illustrate this concept and to categorize its different states. Each axis would include a “hi” and...
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...Science Assessment task Water as a solvent Part 1: Definitions A Amalgam- Amalgam is a substance formed by the reaction of mercury with another metal. Aqueous- Aqueous means "In a solution of water". An Aqueous solution is a solution in which water is the solvent. C Colloid- A colloid is a substance dispersed evenly throughout another substance. Concentrated- A large quantity of substance present in a unit amount of mixture. D Dilute- To dilute a liquid is to make it thinner or weaker by adding water or another solvent to it. E Eutectic- Eutectic point is the lowest temperature at which the eutectic mixture can exist in liquid phase. I Immiscible- Not forming a homogeneous solution when 2 or more liquids are added together. Example, water and oil. Insoluble- Matter that cannot be dissolved. M Miscible- When 2 liquids form a homogeneous mixture when added together. N Non-polar- A hydrophobic (water-hating) chemical group. P Polar- A hydrophilic (water-loving) chemical group. Precipitate- The formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion in a solid. E.g sedimentation or settling. S Saturated- Holding as much water or moisture as can be absorbed. Solute- The minor component in a solution, dissolved in the solvent. Solution- A homogeneous mixture composed of two or more substances. Solvent- The major component in a solution, the solute is dissolved in the solvent. Suspension- A suspension is...
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... Define the following terms and use them in your answers below. - Solubility: The greatest quantity of a solute that can be dissolved into a solvent - Soluble: When a substance can be dissolved into a solvent. Ex: sugar can be easily dissolved into coffee or tea. - Insoluble: When a substance cannot be dissolved into a solvent. Ex: oil cannot be dissolved into water. - Hydrophilic: Describes a substance that can easily be mixed or dissolved into water. Ex: salt - Hydrophobic: Describes a substance that cannot be dissolved or mixed into water. Ex: oil - Density: The amount of matter in a certain area. You can calculate the density bye dividing the mass by the volume. 1) Explain what happens when the oil was added to the water? When the oil was added to the water, it floated to the top because it is hydrophobic and it isn’t soluble in water. 2) Which substance is on the top and why? The oil is on top because it is less dense therefore it’s lighter and it floats to the top. 3) Classify the state of matter of the substances used and produced. The oil, water and food colouring are liquids. The Alka-Seltzer tablet is a solid that is soluble so when it dissolves into the water, it becomes carbon dioxide gas. 4) What type of mixture was produced? How do you know? A heterogeneous and homogeneous mixture was created. The water/food colouring and oil did not mix because oil is hydrophobic and you can easily see the two different substances and you can also see the...
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...Exercise 116 in Ch. 10 Free radicals (see Problem 115) are also important in many environmentally significant reactions. For example, photochemical smog, which forms as a result of the action of sunlight on air pollutants, is formed in part by the following two steps. NO_2 □(→┴(UV LIght) ) NO+O O+O_2→ O_3 The product of this reaction, ozone, is a pollutant in the lower atmosphere. Ozone is an eye and lung irritant and also accelerates the weather of rubber products. Write Lewis structures for each of the reactants and products in the preceding reactions. Valence electrons: O has 6 and N has 5 Total valence electrons: 1N(5)+2O(6) = 5+12=17 According to the book Nitrogen does not have an octet. NO = 5+6= 11 and O is 6 O(6)+2O(6)=18 .. .. . .. .. :O=N-O: ⟶∶N=O: + :O: .. .. .. .. .. :O:+:O≡O:⟶:O=O-O: .. Exercise 132 in Ch. 11 Aerosol cans carry clear warnings against incineration because of the high pressures that can develop upon heating. Suppose a can contains a residual amount of gas at a pressure of 755 mm Hg and a temperature of 25 °C. What would the pressure be if the can were heating to 1155 °C? P1V1/T1 = P2V2/T2 P1=755mm Hg T1=25 °C T2=1155 °C Volume is constant. P_2=(P_1 V_1 T_2)/(T_1 V_2 ) P_2=((755mm Hg)(1)(1155°C))/((25°C)(1)) P2=34881mmHg Exercise 104 in Ch. 12 Water does not easily remove grease...
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...Thanks. All formal papers must be double-spaced and paragraphs indented Polarity Paper Polarities and polarity management We have all encountered stubborn problems that never seem to go away. These situations are not really problems waiting to be solved, but instead dilemmas in need of management. We all face dilemmas in our personal and professional lives. These are ongoing, unsolvable issues and unfortunately are unavoidable. According to Johnson (1998), Polarity Management is an insightful way to understand and succeed in mastering some of life’s most complex situations. Polarity management is a method of dealing with complex situations by looking at all aspects of the situation. Seidler (2009) describes polarity management as a model that helps us deal with all dilemmas in life. This approach facilitates the consideration of all perspectives to a situation, thereby avoiding the one right-answer approach. The most comprehensive decisions seek the advantages of all alternatives to a situation. When encountering a challenging condition, we must first determine if it is a problem we can solve, or an ongoing polarity/dilemma that must be managed. Johnson (1998) suggests two questions for determining whether an issue is a problem or polarity: 1. Is the issue an ongoing challenge? 2. Is the dilemma opposite points of view interdependent? For every dilemma there exist polarities - interdependent opposites we need to consider in order to create an optimal...
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...Extraction of DNA from an Onion Molecular biologists and biochemists are involved with research in finding out as much as possible about the DNA in plants and animals. Although DNA was discovered in the 1950’s, there still remains a lot to be known about it, especially how it is used to determine the physical traits that we all have, and how it regulates the workings of the body. We should always remember that DNA is just a chemical named deoxyribonucleic acid. Because it is a chemical, we can do reactions with it just like we can work with any other chemical. In this lab, we will use the chemical properties of DNA to extract it from the cells of onions. Experiment: Note: You should write all observations from this lab in the observation section on the third page of this lab. These observations will account for a large part of your grade, so be neat and complete! 1) Prepare a buffer solution by pouring the following into a clean 250 mL Erlenmeyer flask: - 120 mL of water (distilled water, if available) - 1.5 grams of sodium chloride (table salt) - 5.0 grams of baking soda (sodium hydrogen carbonate) - 5.0 mL of shampoo or liquid laundry detergent What buffer solutions are used for: This buffer solution is used in this lab for several reasons. First of all, the saltiness and acidity (pH) of the solution is very close to that in living things; as a result, the DNA will like to dissolve into this solution. Secondly...
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...around 30 gram of raw prawn crackers were fried ,than observe the changes before and after the frying process. 1-Results after mixed the oil and water Discussion The result had showed the determination of miscibility of oil water. According to the result of time to revert 80% separation, when the proportion of water and oil were near to equal, the more time it take to have separation.The miscibility is the ability of two liquids to mix with each to form a homogeneous solution.Miscibility is often expressed as a wt/wt%, or weight of one solvent in 100 g of final solution. If two solvents are totally miscible in all proportions, their miscibility is 100%. [1] And the experiment require the 80% and not 100% were based on the polarity. Water is the polar molecule and vegetable oil is not.Polarity is when one end is positively charged while the other end is negatively charged. Each water molecule is made of two hydrogen atoms and one oxygen atom. Only other polar molecules can dissolve in water because polar molecules dissolve only in polar solvents and non-polar molecules dissolve only in non-polar solvents.The reason why oil...
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...Boiling Points and Intermolecular Forces Purpose: The purpose of this lab exercise is to test the theory and rules for London and dipole-dipole forces and using VSPER theory relate how these forces interact to affect the boiling points of hydrogen compounds of elements in groups 14 through group 17. Question: What is the trend in boiling points of the hydrogen compounds of elements in groups 14-17? Hypothesis: a) I predict that group 14 will have the lowest boiling point for each number of electrons, 15 second, 16 third and 17 fourth. This is because as you follow the groups each one has one less bonded hydrogen which should make it more polar and harder to separate. I also predict that the element highest up in each group on the periodic table will have the lowest boiling point and then second, third and fourth. This is because as the molecules go down they get bigger meaning they have more atoms giving them more london forces making them harder to separate. Analysis: b) c) Group 14: - CH4 is a tetrahedral shape so the difference C and H have in electronegativty does not matter because the forces cancel out making this a non-polar molecule. Only having 10 electrons, CH4 has almost no london forces attracting it together, because of these two factors CH4 ends up having a very low boiling point. - SiH4 is a tetrahedral shape so the small difference Si and H have in electronegativty does not matter because the forces cancel out making this a non-polar molecule. Only...
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...of Human Resources Date: October 5, 2012 Subject: Polarity Management: Autocratic vs. Participatory Management You’ve heard the term polar opposites it is used to describe objects, situations, or even people that are very different. North and South poles; yin and yang, dark and light are just a few of the hundreds of phrases used to illustrate polar opposites and their distinct differences. The term polar opposites are often used to brand or categorize things we like or good things versus things we don’t like or bad things. Polarities are persistent issues that are inevitable and unsolvable. The issues or conflicts seem very diverse, but operate at the same time. Sometimes a manager will experience a “damned if I do, damned if I don’t feeling, that is when you have a polarity. Polarity management has been around since early 1975 and continues to be a challenge to companies today. Polarities consist of two interdependent opposites that have two or more answers (Johnson, 1998). Polarities are two issues or conflicts on two far reaching ends of the spectrum, which have no reasonable solution. Each spectrum or pole has advantages as well as disadvantages (Noll, 2002). It is very important to recognize instances of polarity in management situations. If one pole is underlined or a solution is developed it leaves the other pole unresolved thus starting a vicious cycle. The value in comprehending polarities is the understanding they cannot be solved, but only be managed...
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...Biology Professor Smith 27 November 2010 Analysis of a Leaf Extract Introduction: Photosynthesis occurs when proteins in plant cells absorb light. Chlorophyll, the most commonly known pigment in plants, absorbs red and blue light, while reflecting the color green. Because of this, many plants are found to be the color green. There are, however, a wide variety of plants that range in color from red to violet. This is due to the different number of plant pigments that compose a plant. One technique that separates and identifies these different pigments is paper chromatography. In paper chromatography, solvent moves up the paper, carrying with it plant pigments. Because plant pigments are not equally soluble in the solvent, they are carried along at different rates, taking up different parts of the visible light system. An interesting question to explore is what other pigments are found in plants besides the obvious, chlorophyll. Using paper chromatography, pigmentation for plant leaves can be determined. Chromatography works because some pigments have a higher affinity for the solvent than others and move at different rates up the filter paper, causing several color bands to be displayed if there is more than one pigment present in the leaves. Based on the bands formed on the filter paper, the retention factor, or Rf , value can be thereby calculated for each pigment. This is done by dividing the distance the pigment traveled by the distance the solvent...
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