...Assignment 3: Mixtures, Compounds, Elements, Ionic and Covalent Bonds By: Karen Owens November 17, 2012 SCI 110 Professor Lawrance Mullen 1. Describe the difference between a mixture and a compound. The difference between a mixture and a compound is that a mixture is a substance made by mixing other substances together. Most of the time two or more substances that are chemically united and they do not exist in fixed proportions of each other. Unlike a compound a mixture can be physically separated into pure compounds or elements. For example a cake is made up of different substances that are mixed together that are separated. A compound on the other hand is just the opposite of a mixture. A compound has a constant composition with fixed ratio of elements. It can have properties different from its constituents as a new substance is formed when they are chemically combined. The difference is that a compound can only be separated by chemical methods. That is like taking platinum and gold and melting them both down together. You get platinum gold which is a mixture of two elements combined together. 2. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? You can tell the difference because a compound is a mixture of two or more elements. An element on the other hand is a single thing. It is actually divided into pure substances and mixtures. When we have two or more things that are not chemically combined that is called...
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...our chemistry unit, we examined 9 compounds (ascorbic acid, calcium carbonate, calcium chloride, citric acid, magnesium sulfate, sodium bicarbonate, sodium carbonate, sodium chloride, and sucrose). Out of those 9 compounds, a mystery mixture was made using 2 of them. I then identify which 2 compounds made the mystery mixture. In order to identify the 2 compounds used in the mystery mixture, I evaluated the physical and chemical characteristics of the compounds. From the physical appearance of the mystery mixture, it seems that there are only 2 types of compounds. You could see that there were only 2 because 1 of the compounds was very fine and powdery, while the other one was sandy and crystalised. I have determined the compounds in...
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...interaction between the stationary phase and solute. The liquid or gaseous phase passes through a porous gel which separates the molecules according to its size. The pores are normally small and exclude the larger solute molecules, but allows smaller molecules to enter the gel, causing them to flow through a larger volume. This causes the larger molecules to pass through the column at a faster rate than the smaller ones. Affinity Chromatography This is the most selective type of chromatography employed. It utilizes the specific interaction between one kind of solute molecule and a second molecule that is immobilized on a stationary phase. For example, the immobilized molecule may be an antibody to some specific protein. When solute containing a mixture of proteins are passed by this molecule, only the specific protein is reacted to this antibody, binding it to the stationary phase. This...
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...and Conversions Chem 100 Spring 2014 Classification of Matter Chemistry is a branch of physical science, concerned with the study of the composition, properties and behavior of matter. Matter is anything that occupies space and has mass. Forms of energy are NOT matter. Heat and light, for example, do not occupy space and have no mass. Consider the different forms of matter and energy in this picture. 3 Chem 100 Spring 2014 Classification of Matter We classify matter so that we can understand it better. One way to classify matter is as pure substances or mixtures. 4 Matter Pure Substances Mixtures Chem 100 Spring 2014 Classification of Matter – Pure Substances Pure Substances: have the same composition throughout, and from sample to sample. can be further classified as either elements or compounds. 5 Pure Substances Elements Compounds Chem 100 Spring 2014 Pure Substances - Elements An element is a substance that cannot be broken down into simpler substances even by a chemical reaction. 6 Chem 100 Spring 2014 Elements and their Symbols Element symbols often consist of one or two letters of the element’s name. Examples: carbon: C calcium: Ca 7 Chem 100 Spring 2014 Elements and their Symbols List of Elements and their symbols: Need to know by Exam I D2L Handout Content Page 8 Chem 100 Spring 2014 Atoms Matter is composed of atoms. An atom is the smallest...
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... 9 Mixture – is a combination of two substances in such a way that no chemical reaction occurs between the components and you can separate them again. A mixture is a material system made up of two or more different substances which are mixed but are not combined chemically. The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation. Examples of Mixtures sand and water salt and water sugar and salt ------------------------------------------------- Elements are chemically the simplest substances and hence cannot be broken down using chemical methods. Elements can only be changed into other elements using nuclear methods. An element is a type of matter composed of atoms that all have exactly the same positive charge on their nuclei. In other words, all atoms of an element have the same ------------------------------------------------- Examples of Elements ------------------------------------------------- aluminum, selenium, zinc, magnesium, carbon, mercury, gold, arsenic, lead and sodium. ------------------------------------------------- Compound is a chemical species that is formed when two or more atoms join together chemically, with covalent or ionic bonds. A compound is a substance formed when two or more chemical elements are chemically bonded together. Chemical compounds can be broadly classified into two categories, namely, organic compounds and inorganic compounds. Organic compounds are...
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...The purpose of this lab was to purify crude product by column chromatography. The crude product to be purified in this lab was acetylferrocene contaminated with ferrocene. Column chromatography is a technique that utilizes the liquid solid absorption method. This technique has the advantage by isolating more of the product that need to be analyzed. In Column Chromatography the mixture that is being examined, mixture of our product or compound is dissolved in small amount solvent that is then placed on top of the column. Finely packed solid absorbent (silica gel) act as the stationary phase. In order for the mixture to move down the column a eluting solvent (mobile phase) is placed. The separation of the organic compounds depends on how...
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...Distillation of water and ethanol by Harold van Schevensteen The process of simple distillation is a method of separating mixtures based on their differences in volatility in a boiling liquid mixture. We find out, however, that using this process, a mixture of water and ethanol cannot be separated fully. The latter can only be purified to approximately 96%. To get to this point, we go through a process whereby through distillation, we reduce the proportion of water in the mixture and increase that of ethanol. For example, if we were to distill a 50/50 mixture of ethanol and water, the distillate would be 80% ethanol and 20% water. Distilling this new mixture produces a mixture of 87% ethanol and 13% water. This goes on until we reach a ratio of 95.63% ethanol and 4.37% water, at which we reach a point called the azeotropic point of the mixture. At this stage, the mixture is called a positive azeotrope, which is defined when the ratio of the constituents cannot be further changed by simple distillation. This occurs because any further boiling of the mixture will result in a vapour who’s ratio of constituents is the same as the original mixture. The closer we get to this point, the lower the boiling point of the mixture as a whole. Ethanol has a boiling temperature of 78.4°C and water one of 100°C. When we have reached the azeotropic point, the mixture as a whole boils at a temperature of 78.2°C. Any further distillation will see the azeotrope boil at a temperature which...
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...MECHANICAL ENGINEERING BULUMA MARK EUGINE F18/1494/2011 GROUP 4 EXPERIMENT 6: THIN LAYER CHROMATOGRAPHY. THE OBJECTIVE OF THE EXPERIMENT. 1. To separate the unknown amino acids mixture into its various components. 2. To identify the amino acids present in the unknown amino acid mixture. THE THEORY BEHIND THE EXPERIMENT. Chromatography is a method of separating a mixture into its components, by use of heterogeneous equilibrium established during the flow of the solvent called a mobile phase through a fixed (stationary) phase. The stationary phase can be either solid or liquid, while the mobile phase can either be a liquid or a gas. Therefore, chromatography can be classified as; solid- liquid, liquid- liquid, or gas- liquid. Experimentally, chromatography can be carried out in columns or in layers. The column chromatography uses a vertical tube packed with a medium/ adsorbent. The layer chromatography uses a thin layer embedded unto a plate unto which the samples are introduced. The thin film stationary phase may be: 1. A liquid (partition chromatography). Example is paper chromatography. 2. A finely divided adsorbent solid. (Adsorption chromatography). Example is Thin Layer Chromatography. INTRODUCTION TO THE EXPERIMENT. Thin layer chromatography (TLC) is a chromatography technique used to separate mixtures.[1] Thin layer chromatography is performed on a sheet of glass, plastic, or aluminum foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium...
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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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...PHYSICAL CHANGE Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but cannot usually be used to separate compounds into chemical elements or simpler compounds.[1] Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances. In general a physical change is reversible using physical means. For example salt dissolved in water can be recovered by allowing the water to evaporate. A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, colour, volume and density. An example of a physical change is the process of tempering steel to form a knife blade. A steel blank is repeatedly heated and hammered which changes the hardness of the steel, its flexibility and its ability to maintain a sharp edge. Methods Heating and cooling Many elements and some compounds change from solids to liquids and from liquids to gases when heated and the reverse when cooled. Some substances such as iodine and carbon dioxide go directly from solid to gas in a process called sublimation...
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...States of Matter Gases, liquids and solids are all made up of microscopic particles, but the behaviors of these particles differ in the three phases. The following figure illustrates the microscopic differences. | | | Microscopic view of a gas. | Microscopic view of a liquid. | Microscopic view of a solid. | Note that: * Particles in a: * gas are well separated with no regular arrangement. * liquid are close together with no regular arrangement. * solid are tightly packed, usually in a regular pattern. * Particles in a: * gas vibrate and move freely at high speeds. * liquid vibrate, move about, and slide past each other. * solid vibrate (jiggle) but generally do not move from place to place. Liquids and solids are often referred to as condensed phases because the particles are very close together. The following table summarizes properties of gases, liquids, and solids and identifies the microscopic behavior responsible for each property. Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior | gas | liquid | solid | assumes the shape and volume of its container particles can move past one another | assumes the shape of the part of the container which it occupies particles can move/slide past one another | retains a fixed volume and shape rigid - particles locked into place | compressible lots of free space between particles | not easily compressible little...
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...The Determination of Boiling Points and Melting Points of Organic Compounds During this laboratory session, we will practice determining the boiling point of a liquid organic compound and the melting point (or we could call it the freezing point) of a solid organic compound. The boiling point of a liquid is the temperature at which the pressure of the vapor above a liquid equals the existing pressure. As we heat a liquid, the pressure of the vapor above the liquid slowly increases. When this pressure equals the pressure existing in the container, the liquid begins to boil– the liquid turns to vapor. If not contained, the vapor will “escape” into the atmosphere. In other words, the liquid evaporates. If the vapor is contained, and then passed through an area where the temperature is lower, the vapor will “condense” and enter the liquid state again. This would be a distillation. Atmospheric pressure is approximately 760 mm Hg; i.e., the weight of a column of mercury measuring 1 mm2 and 760 mm tall. This equates to about 29.7 inches of mercury. If we reduce the pressure above the sample that we are heating, we can reduce the boiling point of the liquid. This is referred to as a vacuum distillation or carrying out a distillation in vacuo. For example, while water boils at 100oC (or 212° F) at 760 mm Hg, it boils around 22oC at 20 mm Hg. The boiling point of a liquid is a physical characteristic of a compound. Many factors go into the estimation of the boiling point of a liquid such...
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...3. INTRODUCTION Organic compounds are isolated either from natural sources or from reactions mixtures. These compounds are seldom pure and are usually contaminated with small amounts of other similar compounds, which are found to exist together or formed during the reaction. In order to characterize them, it is important to purify them. 4. PROCESSES FOR PURIFICATION 1. Crystallization 2. Sublimation 3. Distillation 4. Chromatography 5. Differential Extraction 6. Qualitative Analysis 5. 1. CRYSTALLIZATION Aim To separate a solid compound in pure and geometrical form. Principle A saturated solution of the impure substance in a suitable solvent is made at a temperature higher than the room temperature. On cooling this solution, the substance reappears in the form of well shaped crystals. Process Purification by crystallization involves the following steps: Choice of solvent Preparation of solution Filtration of the solution Separating the crystals Drying of crystals Example Crystallisation of Phthalic acid 6. 2. SUBLIMATION Aim To separate volatile solids, which pass directly into vapour state on heating from a non-volatile solid. Principle A mixture of solid substances, such as camphor, benzoic acid, ammonium chloride, iodine etc., containing non-volatile substances, when heated, change directly into vapour without passing through the liquid state. Process 7. Fig :-Sublimation 8. 3. DISTILLATION Aim To separate a solution of a solid in a liquid and for separating a solution...
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...Assignment #3 Documented Essay: Chemistry SCI 110 Professor Denise Stiglich Describe the difference between a mixture and a compound As described in the text book, a mixture has unlike parts and a composition that varies from sample to sample (Tillery, p. 200). The book provides an example of sand from a beach. It has a variable mixture of such things as bits of rocks, minerals and sea shells (Tillery, p. 200). A compound is a pure substance that can be decomposed by a chemical change into simpler substances with a fixed mass ratio (Tillery, p. 201). So the difference is that a compound is made up of two or more elements that have a composition that is constant. And a Mixture is an aggregate of two or more substances that are not chemically united. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? The way you can tell if a pure substance is a compound or an element is that an element is made up of one kind of atom. For example, gold is an element. If you were to keep cutting the gold until you only had one particle of gold that couldn’t be cut anymore, you would have one atom. A substance that is a compound has two or more elements. For example, water is a compound that is made up of two different elements, hydrogen and oxygen. What is the difference between an ionic and a covalent bond? As stated in the text book, an ionic bond is defined as the chemical bond of...
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...The Determination of Boiling Points and Melting Points of Organic Compounds During this laboratory session, we will practice determining the boiling point of a liquid organic compound and the melting point (or we could call it the freezing point) of a solid organic compound. The boiling point of a liquid is the temperature at which the pressure of the vapor above a liquid equals the existing pressure. As we heat a liquid, the pressure of the vapor above the liquid slowly increases. When this pressure equals the pressure existing in the container, the liquid begins to boil– the liquid turns to vapor. If not contained, the vapor will “escape” into the atmosphere. In other words, the liquid evaporates. If the vapor is contained, and then passed through an area where the temperature is lower, the vapor will “condense” and enter the liquid state again. This would be a distillation. Atmospheric pressure is approximately 760 mm Hg; i.e., the weight of a column of mercury measuring 1 mm2 and 760 mm tall. This equates to about 29.7 inches of mercury. If we reduce the pressure above the sample that we are heating, we can reduce the boiling point of the liquid. This is referred to as a vacuum distillation or carrying out a distillation in vacuo. For example, while water boils at 100oC (or 212° F) at 760 mm Hg, it boils around 22oC at 20 mm Hg. The boiling point of a liquid is a physical characteristic of a compound. Many factors go into the estimation of the boiling point of a liquid such...
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