...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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...Does Salt effect the Boiling Temperature of Water? By Jason Project Design Plan Water freezes at 32°F and boils at 212 °F. Dissolved substances such as salt lower the freezing point of water. This is why salt is sprinkled over icy pavement or wet roads in winter. It causes the temperature of the water to reach less that 32°F to form ice. Does it also have an effect on the boiling point of water? Does the quantity of salt added effect the boiling point? My experiment is to find out what effects salt will have on the temperature of boiling water. The hypothesis of my experiment is that if I add more salt then the temperature of the boiling water will increase. I believe the more salt added to the water the higher the boiling temperature is going to be. I will be using 2 cups of water as a base in a 2 quart stainless steel pot. I will add 1 tsp of salt, 2 tsp of salt and 4 tsp of salt and measure the temperature of the water. Literature Review If you heat up two pots of water one with tap water and one with tap water and 20 percent salt water, the pot with the salt water will boil before the pot without salt water. The heat capacity of water is higher than salt water. This means that it takes less energy to increase the temperature of salt water than it does unsalted water. Thus salt water warms up quicker and gets to a boiling point faster than unsalted water. (Dammann, 2013) Dissolving table salt into water will lower the overall vapour pressure of...
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...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 as...
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...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 as...
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...Group No. 6 Experiment No. 1 MELTING POINT AND BOILING POINT OF ORGANIC COMPOUNDS ABSTRACT One of the methods to identify an organic compound is by determining its physical properties. In this experiment, we will only looking for their melting point and boiling point on the effects of the chemical structures. Melting point is defined as the temperature at a specific pressure which the solid and liquid phases are in equilibrium with each other. The boiling point is used to characterize a new organic liquid and knowledge of the boiling point helps to compare one organic compound to another, as in identifying unknown organic compound. The purpose of this experiment is to determine the effects of: intermolecular forces of attraction and geometric isomerism in the melting point of compounds; purity on the melting point range of organic compounds; intermolecular forces of attraction and branching on the boiling point of organic compounds. To do the experiment, Thomas Hoover apparatus is used for determine the melting point and micro test for the boiling point. Salicylic acid has the highest melting point between the rest of the sample with 152.5-157.1°C range and naphthalene has melted fastest as it melted at 75.8-80.6°C for the first part of the melting point experiment. The melting point of fumaric acid is between 278-286°C which is higher than Maleic acid with 122.3-131.8°C. Meanwhile, the pure urea has 127-132.2°C melting point which is higher than impure urea with 98.5-128...
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...1 ) Explain how kinetic energyand potential energy determine the properties of the three states and phase changes, what occurs when heat is added or removed from a substance and how to calculate the enthalpy change. Answer In a gas, the potential energy (energy of attraction) is small to the kinetic energy thus, on average, the particles are far apart. This large distance has several macroscopic consequences : a gas fills its container, is highly compressible, and flows easily through another gas. In a liquid , attractions are stronger because the particles are touching, but they have enough kinetic energy to move randomly around each other.Thus, a liquid conforms to the shape of its container but has a surface ; It resists an applied force and thus compresses very slightly ; and it flows, but much more slowly than gases. In a solid, the attractions dominate the motion so much that the particles are fixed in position relative to one another, just jiggling in place. Thus, a solid has its own shape, compresses even less than liquids, and does not flow significantly. Each phase change has a name and an associated entalphy change : Gas to liquid, and vice versa. As the temperature drops, the molecules in the gas come together and form a liquid in the process, changing from a liquid to gas, is vaporization. Liquid to solid, and vice versa. As the temperature drops further, the particles move slower and become fixed in position in the process of freezing ; In common speech...
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...Determination of boiling point and melting point of the organic liquids, in practice determining the boiling point of ethyl and Isopropyl Alcohol and the melting point of benzoic acid and Urea. However, 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 presented in the container, the liquid begins to boil– the liquid turns to vapor. Many factors affect the boiling point and melting point of an organic compound, and one of which is the molecular structure. Purity and branching also affects the boiling and melting point of a compound. There are three trends that affect the boiling and melting points and one of these trends is the relative strength of the four intermolecular attractions is factor significally affects the boiling point and the melting point of a compound. INTRODUCTION Internationally, boiling points is a useful physical property for demonstrating the purity of an organic compound. Boiling point is the temperature at which the vapor pressure of a liquid equal atmospheric pressure or some other applied pressure. A boiling point is commonly measured when the liquid heated. The boiling temperature is measured as distillation vapor covers the bulb of a thermometer suspended above the boiling liquid. Typically, the most accurate boiling point measurement is the...
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...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 of two liquids whose boiling points are different. Principle Distillation involves the conversion of a liquid into its vapors upon heating and then cooling the vapors back into the liquid. Depending on the difference in boiling points of liquids. Types of distillation Simple Distillation Fractional Distillation Distillation Under Reduced Pressure or Vacuum Distillation Steam Distillation 9....
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...Chang: Chemistry 7th Edition - Chapter 11 CH116 General Chemistry II INTERMOLECULAR FORCES Inter-molecular Forces Have studied INTRAmolecular forces—the forces holding atoms together to form molecules. Now turn to forces between molecules — INTERmolecular forces. Forces between molecules, between ions, or between molecules and ions. Table 13.1 Summary of Intermolecular Forces Ions Dipoles Induced Dipoles (Overhead & book p 585) Covalent bond energies 100-400 kJ/mol Attractive forces between ions 700-100 kJ/mol Intermolecular attractions less than 15% of bond energies Intermolecular Forces Ion-Ion Forces Na+ — Cl- in salt. These are the strongest forces. Lead to solids with high melting temperatures. NaCl, mp = 800 oC MgO, mp = 2800 oC Intermolecular Attractions Coulomb’s Law Force ~ (n+)(n-)/d2 Distance - twice the distance = 1/4 the force Charge on the Ion Magnitude of the dipole Composition - Solids and Liquids are closer so composition has greater role in attractive forces Attraction Between Ions and Permanent Dipoles Water is highly polar and can interact with positive ions to give hydrated ions in water. Attraction Between Ions and Permanent Dipoles Water is highly polar and can interact with positive ions to give hydrated ions in water. Dissolving Ionic Solids Attraction Between Ions and Permanent Dipoles Many metal ions are hydrated. It is the reason metal salts dissolve in water. Attraction Between Ions and Permanent...
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...difference from the sublimate obtained from 5.0014 g to 0.3213 g, respectively. Thus, the measured sublimate showed the low percentage recovery of the said compound. The sublimate was then subjected to melting point determination together with the pure benzoic acid through the oil bath. The oil bath was used since it is able to measure temperatures even those beyond 100 °C and are highly recommendable for compounds which have higher boiling points. As it was seen in the results for the melting point determination, the sublimate started to melt at 116 °C and stopped melting at 120 °C while the pure benzoic acid started to melt at 120 °C and ended at 121 °C. The temperatures measured indicated that the pure benzoic acid has a higher vapour pressure than the sublimate. INTRODUCTION Sublimation is the direct vaporization of a solid by heating without passing through the liquid state. [1] The process of sublimation in this experiment is used to purify the impure benzoic acid. The impurities in the benzoic acid have amino compounds that are present in a larger extent and must be removed because of phenyl and benzyl compounds that seriously affect the product.[3] This process occurs if the vapour pressure of the substances greater than the atmospheric pressure at the melting point.[2] The process of purification involved in sublimation is applicable for impurities which are non-volatile or with lower vapor pressure than the pure compound or substance. The objectives of this experiment...
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...TLC, paper chromatography, and gas chromatography. Paper chromatography is one of the important chromatographic methods. Paper chromatography uses paper as the stationary phase and a liquid solvent as the mobile phase. In paper chromatography, the sample is placed on a spot on the paper and the paper is carefully dipped into a solvent. The solvent rises up the paper due to capillary action and the components of the mixture rise up at different rates and thus are separated from one another. Distillation Simple distillation is a method used for the separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points. The distillation process involves heating a liquid to its boiling points, and transferring the vapours into the cold portion of the apparatus, then condensing the vapours and collecting the condensed liquid in a container. In this process, when the temperature of a liquid rises, the vapour pressure of the liquid increases. When the vapour pressure of the liquid and the atmospheric pressure reach the same level, the liquid passes into its vapour state. The vapours pass over...
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...CHARACTERISTICS OF REFRIGERANTS Pure R-12 (CC 1425F425) is colorless. It is odorless in concentrations of less than 20 percent by volume in air. In higher concentrations, its odor resembles that of carbon tetrachloride. It has a boiling point of -21°F at atmospheric pressure. At ordinary temperatures under a pressure of approximately 70 psig to 75 psig, R-12 is liquid. Because of R-12’s low boiling point at atmospheric pressure, you must always protect your eyes from contact with liquid R-12; the liquid will freeze the tissues of the eyes. Always wear goggles if you is to be be exposed to R-12. R-22 (CHC1F425) and R-11(CC1435F) are colorless, nonexclusive, nonpoisonous refrigerants with many properties similar to those of R-12. Because of the similarities between R-22, R-11, and R-12, only R-12 is discussed. Mixtures of R-12 vapor and air, in all proportions, will not irritate your eyes, nose, throat, or lungs. The refrigerant will not contaminate or poison foods or other supplies with which it may come in contact. The vapor’s nonpoisonous. However, if R-12 concentration becomes excessive, it can cause you to become unconscious or cause death because of lack of oxygen to the brain.R-12 is nonflammable and nonexclusive in either liquid or vapor state. R-12 will not corrode the metals commonly used in refrigerating systems.R-12 is a stable compound capable of undergoing the physical changes required of it in refrigeration service...
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...BUET Submitted by, Md. Touhidul Islam Std. Id- 1202011 Level- 3, Term- 1 Dept. – Ch.E Group- 03 (A1) ------------------------------------------------- 1.0 SUMMARY The objective of this experiment was to study Soxhlet Extractor and to determine the percent extraction of oil from oil cake and percent recovery of solvent used for extraction. In this experiment, a paper thimble was weighed and then measured amount of oil cake was taken in the thimble and placed in the Soxhlet holder. N-hexane, which was used as the solvent, was measured in a round bottom flask and then after setting up the apparatus, was heated by an electric heater up to its boiling point. The n-hexane vapor rose up to the condenser and absorbing heat from the cooling water it was condensed which fell in the thimble. Oil was extracted from the oil cake by n-hexane and after the level of the oil-hexane mixture rose to a certain...
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...Questions: 1. At what temperature does the water begin to boil and start turning into vapor? 100 degrees Celsius. 2. At the boiling point when you have a mixture of liquid and vapor and you are applying heat, does the temperature change? No. 3. After all of the liquid has boiled off and turned into vapor, does the temperature increase? Yes. 4. How does the vapor volume compare with the original amount of liquid volume you had when you started the experiment? Vapor volume increased as the liquid volume decreased until the liquid volume reached zero liters. 5. At what temperature does the vapor start condensing into liquid? 144.83 degrees Celsius. 6. How does the volume of water you have now ( at room temperature) compare with the volume of water you started out with? Same volume of .147 liters. 7. While the water is freezing does the temperature continue to deop? Yes. 8. Is the ice volume higher or lower than the original volume of water? The ice volume is higher. 9. Why are they different? Ideal gas law states an increase in pressure yields a higher temperature. 10. At what temperature does the ice begin to melt? .003 degrees Celsius. 11. Is it the same as the freezing point when the pressure was 4 atm? No. 12. At what temperature does the water begin to boil? 81.663 degrees Celsius. 13. Is it the same as the boiling...
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...goggles, apron, hair restraints, Bunsen burner, heated water, harmful metals, breakable glass containers Materials: goggles and apron, beaker (250 mL or 400 mL) , hot plate/burner with ring stand, ring, and wire gauze, test tube(18 x 150 mm), plastic foam cup, thermometer, balance Procedure: 1. Put on goggles and apron. 2. Fill beaker half way with water. Put beaker on ring stand with wire gauze. Heat beaker with water to boiling point. 3. Fill test tube half way with metal 4. Put a weight boat on the balance. Pour metal from test tube into the weight boat. Record weight and pour metal back into test tube. 5. Put test tube of metal into the water. Leave inside the beaker of boiling water while completing step 6 and 7. 6. Use the foam cup as calorimeter. Measure mass and record. 7. Fill foam cup with room temperature water and record mass. 8. Put thermometer in test tube and record temperature. 9. Put thermometer inside the foam cup and record the temperature of the water. 10. Take test tube out of the boiling water and immediately pour inside the foam cup. 11. Stir the water and record highest temperature. 12. Pour water out, making sure no metal escapes. Let metal dry on paper towel. 13. Repeat the procedures if time permits. Return the metals to the teacher. Raw Data/ Observations Table(s): Mass Data | Temperature Data | Material | Mass | Material | Temperature | Metal | 104.89 grams | Metal | 97.3 degrees Celsius...
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