DOCSLIB.ORG

Absolute Prediction of the Melting and Freezing Points of Saturated Hydrocarbons Using Their Molar Masses and Atume’S Series

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Absolute Prediction of the Melting and Freezing Points of Saturated Hydrocarbons Using Their Molar Masses and Atume’S Series Advanced Journal of Chemistry-Section A, 2020, 3(2), 122-130 Available online at : www.ajchem-a.com ISSN Online: 2645-5676 DOI: 10.33945/SAMI/AJCA.2020.2.2 Original Research Article Absolute Prediction of the Melting and Freezing Points of Saturated Hydrocarbons Using Their Molar Masses and Atume’s Series Atume Emmanuel Terhemen* Faculty of Natural sciences, University of Jos PMB 2084, Jos Plateau State, Alumni, Nigeria A R T I C L E I N F O A B S T R A C T Received: 08 June 2019 This study was conducted to apply the Atume’s series in the absolute prediction Revised: 24 July 2019 of melting and freezing points of a wide range of saturated liquid and solid Accepted: 07 August 2019 hydrocarbons. The calculated results that were obtained, shows that a range of Available online: 20 August 2019 92% to 99% accuracy was theoretically achieved when compared to experimental results. Basically, precise interpolations were deployed by equating the energies released by frozen liquid molecules to the energies absorbed by their corresponding boiling molecules; which represents their K E Y W O R D S lower and upper energy fixed points respectively. These two fixed points were also found to vary infinitesimally and inversely to each other. The energies Melting point Freezing point absorbed or released, molar masses, and trigonometric properties formed the Atume’s series basis for this method. In branched chain hydrocarbons, the melting points of Atume’s formular their corresponding linear molecules were also used as reference points to Saturated hydrocarbon determine their melting and freezing points; indicating the mathematical relationships between their fixed points and trigonometric properties. G R A P H I C A L A B S T R A C T * Corresponding author's E-mail address: [email protected] Absolute Prediction of the Melting and Freezing… 123 Introduction are proportional to other thermodynamic state functions like: enthalpy, entropy, and The melting and freezing points of pure internal energy, we can conveniently place chemical compounds are intensive properties temperatures on a scale with upper and lower like density and boiling point. More so, energy/temperature fixed points, in order to intensive properties are independent of the determine any unknown thermodynamic amount of substance present. Experimentally, function. All the information from this it has been discovered that, melting point is analysis will be useful in the programming of actually recorded as the range of devices for chemical analysis. temperatures in which the last crystal just disappears [1]. Important definitions and abbreviations The melting point of a substance is the temperature in which it changes state from Atume’s formular for the melting and solid to liquid at atmospheric pressure. The freezing point of n-alkanes is given as: reverse process is called the freezing point; 푀2 which is known as the temperature in which Ms = 퐴푠푏푠 ( ) the substance changes state from liquid to 푒 퐴푠푟 solid at atmospheric pressure. Atume’s formular for the melting and The melting point of a solid is freezing point of all saturated hydrocarbon is approximately the same as the freezing point given as: of its liquid. It is also the temperature in which the rate of melting of a solid equals the rate of 푀2 Ms = [ 퐴푠푏푠 ] Sin ∝ ( ) freezing of its liquid, under a given applied 푒 퐴푠푟 pressure. However, it can also be referred to Where; the temperature in which its solid and liquid Ms = the melting point of straight chain phases coexist in equilibrium, because the hydrocarbon (alkanes). transition between the solid and the liquid is Mb = the melting point of a branched chain so sharp at a negligible temperature hydrocarbon. difference of approximately 0.1 °C. At this M = molar mass of the compound particular temperature, the substance can Asms= Atume’s series for the melting point exist as either solid or liquid [2]. of straight chain alkanes also known as energy Melting point is a physical property often of the lower fixed point (energy loss for used to identify compounds or to check the melting or freezing to occur). purity of the compound. Practically, it is Asbs = Atume’s series for the boiling point difficult to find a melting point. In terms of of straight chain alkanes also known as energy melting accuracy, the best chemists can obtain of the upper fixed point (energy gained for falls within the range of 2-3OC accuracy. This boiling to occur). result is usually sufficient in cases where Asr = Atume’s series for the ratio of Asbs to melting point is used [3]. the ratio of the natural logarithm of Asms. The purpose of this study is to create a ∝ = angular deviation from a new and effective method to calculate all corresponding straight chain isomer as a thermodynamic state functions of a result of conventional inductive effect of hydrocarbon, at any temperature and hydrocarbons in degrees [4]. pressure, by using molar masses of 푝̅ is given as inductive pressure or force compounds and a suitable Atume’s series. per unit volume [5]. Since melting, freezing and boiling points A.E. Terhemen 124 Experimental which have the value of 6.02 × 1023 atoms per unit rise in Kelvin. The results obtained Method from this estimation of Asbs values for C5- Estimation of absolute values for ‘Asbs’ from C30 n-alkanes are shown on Table 1. experimental results 2 From the molar masses of C5-C30 n- From Table 1, Bs ∝ M (퐸푞. 1) alkanes and the experimental results of corresponding boiling points, absolute Assumptions ‘Asbs’ values in g2/mol2K were estimated by 1. ‘A conventional inductive effect exists squaring the mass of one mole of each within the molecule of an n-alkane such alkane molecule and the moles of their that, the carbon atoms at the left and right inverses. This is so because, for as many extremes, pumps electrons into the central elementary entities in each alkane molecule, carbon atoms. are also atoms in 12 grams of carbon-12, Table 1. Absolute estimation of ‘Asbs’ values S/N Compound Formular Molar mass M2 Boiling point ‘Bs’ (Asbs) M2/Bs (M) g/mol-1 g/mol-2 in Kelvin [6] (g2/mol2K) 1 n- pentane C5H12 72 5184 309.1 16.7713 2 n- hexane C6H14 86 7396 341.7 21.6447 3 n- heptanes C7H16 100 10000 371.4 26.9251 4 n- octane C8H18 114 12996 398.7 32.5959 5 n- nonane C9H20 128 16384 423.8 38.6597 6 n- decane C10H22 142 20164 447.9 45.0190 7 n-undecane C11H24 156 24336 468.9 51.9002 8 n-dodecane C12H26 170 28900 489.3 59.0640 9 n- C15H32 212 44944 543.6 82.6784 pentadecane 10 n-eicosane C20H42 282 79524 615.7 129.1603 Figure 1. Assumed conventional inductive effects for n-alkanes 2. The molecule experiences an immediate elastic repulsion of electrons from the central Absolute Prediction of the Melting and Freezing… 125 carbon atom(s), back to the extreme carbon Let us start by integrating 푝̅ because the atom(s) by a force known as Inductive central carbon atoms do not operate as Pressure (푝̅). individuals but as a collective unit. 1 3. The pumping in and out of electrons is From: 푝̅ = (2푁−4)푢푛푖푡푠 extremely fast (becomes slow during freezing process), resulting into kinetic energy from 1 ∫ 푝̅ 푑푝̅ = ∫ 푑푝̅ the molecule. Although, the energy is not high (2푁 − 4) enough to cause dissociation into ions or breakage of the bonds within the molecule. 푝̅ = ln(2푁 − 4) 푢푛푖푡푠 = natural logarithm of 4. As the size of the molecule increase, the the internal molecular energy. conventional inductive effects also increase Generally, an A.P which is equal to [(N-5) with increasing number of carbon atoms. 0.2 + 3.027]2 unit was obtained by dividing After the second carbon atom, the effect dies each ‘Asbs’ value by their ln (2N-4) values. down completely so that a maximum of 2 This is a representation of the external kinetic carbon atoms pumps electrons into the energy for all liquid state n-alkanes and it is central carbon chain from both extremes, known as the Atume’s series for liquid state n- making a total of 4 carbon atoms. This means alkanes’ [5]. the effective repulsion of electrons is Work done for boiling to take place is proportional to 2 (N-2) units which is equal to therefore the product of the internal k (2N-4) units. This implies that B ∝ (2N-4) molecular energy and the external kinetic units. energy of the n- alkanes which is equal to Nevertheless, as the length of the central ‘Asbs’. carbon chain increase, the inductive pressure Asbs = [(N-5) 0.2 + 3.027]2 ln (2N-4). decreases due to the increase in the total cross sectional area or volume. Therefore, the Estimation of absolute values for ‘Asms’ from inductive pressure is inversely proportional experimental results to (2N-4) units i.e. Using the molar masses of C5-C30 n-alkanes 1 1 and the experimental results of their 푝̅ ∝ ==> 퐵푠 ∝ (퐸푞. 2) (2푁 − 4) 푝̅ corresponding melting points, absolute ‘Asms’ values in g2/mol2K were estimated by For a freezing molecule; 푝̅ is equivalent to squaring the mass of one mole of each alkane Asms molecule and the moles of their inverses, for as many elementary entities in each alkane 1 1 푝̅ ∝ ==> 푀푠 ∝ molecule just as there are atoms in 12 grams (2푁 − 4) 푝̅ of carbon-12 which have the value of 6.02 × 1023atoms per unit rise in Kelvin.
Load more

Recommended publications
  • Fish Technology Glossary
    Glossary of Fish Technology Terms A Selection of Terms Compiled by Kevin J. Whittle and Peter Howgate Prepared under contract to the Fisheries Industries Division of the Food and Agriculture Organization of the United Nations 6 December 2000 Last updated: February 2002 Kevin J. Whittle 1 GLOSSARY OF FISH TECHNOLOGY TERMS [Words highlighted in bold in the text of an entry refer to another entry. Words in parenthesis are alternatives.] Abnormalities Attributes of the fish that are not found in the great majority of that kind of fish. For example: atypical shapes; overall or patchy discolorations of skin or of fillet; diseased conditions; atypical odours or flavours. Generally, the term should be used for peculiarities present in the fish at the time of capture or harvesting, or developing very soon after; peculiarities arising during processing should be considered as defects. Acetic acid Formal chemical name, ethanoic acid. An organic acid of formula CH3.COOH. It is the main component, 3-6%, other than water, of vinegar. Used in fish technology in preparation of marinades. Acid curing See Marinating Actomyosin A combination of the two main proteins, actin and myosin, present in all muscle tissues. Additive A chemical added to a food to affect its properties. Objectives of including additives in a product include: increased stability during storage; inhibition of growth of microorganisms or production of microbial toxins; prevention or reduction of formation of off-flavours; improved sensory properties, particularly colours and appearance, affecting acceptability to the consumer; improved properties related to preparation and processing of food, for example, ability to create stable foams or emulsions, or to stabilise or thicken sauces.
    [Show full text]
  • Δtb = M × Kb, Δtf = M × Kf
    8.1HW Colligative Properties.doc Colligative Properties of Solvents Use the Equations given in your notes to solve the Colligative Property Questions. ΔTb = m × Kb, ΔTf = m × Kf Freezing Boiling K K Solvent Formula Point f b Point (°C) (°C/m) (°C/m) (°C) Water H2O 0.000 100.000 1.858 0.521 Acetic acid HC2H3O2 16.60 118.5 3.59 3.08 Benzene C6H6 5.455 80.2 5.065 2.61 Camphor C10H16O 179.5 ... 40 ... Carbon disulfide CS2 ... 46.3 ... 2.40 Cyclohexane C6H12 6.55 80.74 20.0 2.79 Ethanol C2H5OH ... 78.3 ... 1.07 1. Which solvent’s freezing point is depressed the most by the addition of a solute? This is determined by the Freezing Point Depression constant, Kf. The substance with the highest value for Kf will be affected the most. This would be Camphor with a constant of 40. 2. Which solvent’s freezing point is depressed the least by the addition of a solute? By the same logic as above, the substance with the lowest value for Kf will be affected the least. This is water. Certainly the case could be made that Carbon disulfide and Ethanol are affected the least as they do not have a constant. 3. Which solvent’s boiling point is elevated the least by the addition of a solute? Water 4. Which solvent’s boiling point is elevated the most by the addition of a solute? Acetic Acid 5. How does Kf relate to Kb? Kf > Kb (fill in the blank) The freezing point constant is always greater.
    [Show full text]
  • Disrupting Crystalline Order to Restore Superfluidity
    Abteilung Kommunikation und Öffentlichkeitsarbeit Referat Medien- und Öffentlichkeitsarbeit Tel. +49 40 42838-2968 Fax +49 40 42838-2449 E-Mail: [email protected] 12. Oktober 2018 Pressedienst 57/18 Disrupting crystalline order to restore superfluidity When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way. We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold and refreshing slushy with the perfect consistency, constant mixing of the liquid is needed. For example, a slush machine with constantly rotating blades helps prevent water molecules from crystalizing and turning the slushy into a solid block of ice. Imagine now controlling quantum matter in this same way. Rather than forming a normal liquid, like a melted slushy under the sun for too long, quantum matter can form a superfluid. This mysterious and counterintuitive form of matter was first observed in liquid helium at very low temperatures, less than 2 Kelvin above absolute zero. The helium atoms have a strong tendency to form a crystal, like the water molecules in a slushy, and this restricts the superfluid state of helium to very low temperatures and low pressures. But what if you could turn on the blades in your slush machine for quantum matter? What if you could disrupt the crystalline order so that the superfluid could flow freely even at temperatures and pressures where it usually does not? This is indeed the idea that was demonstrated by a team of scientists led by Ludwig Mathey and Andreas Hemmerich from the University of Hamburg.
    [Show full text]
  • Physical Changes
    How Matter Changes By Cindy Grigg Changes in matter happen around you every day. Some changes make matter look different. Other changes make one kind of matter become another kind of matter. When you scrunch a sheet of paper up into a ball, it is still paper. It only changed shape. You can cut a large, rectangular piece of paper into many small triangles. It changed shape and size, but it is still paper. These kinds of changes are called physical changes. Physical changes are changes in the way matter looks. Changes in size and shape, like the changes in the cut pieces of paper, are physical changes. Physical changes are changes in the size, shape, state, or appearance of matter. Another kind of physical change happens when matter changes from one state to another state. When water freezes and makes ice, it is still water. It has only changed its state of matter from a liquid to a solid. It has changed its appearance and shape, but it is still water. You can change the ice back into water by letting it melt. Matter looks different when it changes states, but it stays the same kind of matter. Solids like ice can change into liquids. Heat speeds up the moving particles in ice. The particles move apart. Heat melts ice and changes it to liquid water. Metals can be changed from a solid to a liquid state also. Metals must be heated to a high temperature to melt. Melting is changing from a solid state to a liquid state.
    [Show full text]
  • A Possible Force Mechanism Associated with the Freezing of Water in Porous Materials
    A Possible Force Mechanism Associated with the Freezing of Water in Porous Materials LORNE W. GOLD Division of Building Research, National Research Council, Ottawa, Canada The thermodynamic equilibrium conditions for a water-ice interface in a pore of a porous medium are derived. It is found that, taking the geometry and physical dimensions of the pore into consideration, a positive pressure must develop between the ice and the solid in order for equilibrium to be maintained when the temperature at the freezing plane is depressed. A simple model utilizing this mecha• nism exhibits the same properties as a frost-heaving soil. The in• fluence of air in the pores is briefly discussed. #WHEN WATER is present in porous materials and is allowed to freeze, a force may be developed which is not directly related to the expansion that occurs when water changes to ice. Although many observations have been made on this phenomenon, par• ticularly in the field of soil mechanics, a satisfactory explanation of the origin of this force has not appeared. Experiments to date indicate how the magnitude of this force depends on certain physical characteristics of the system. The following are some of the facts observed during experiments that a theory on the origin of this force must explain: 1. During the freezing process, the freezing plane may remain stationary while the ice phase continues to grow. When this occurs, the frozen portion is displaced rela• tive to the unfrozen and a layer of ice, often called an ice lens is formed. The dis• placement may be microscopic or it may amount to several inches.
    [Show full text]
  • Understanding Freezing Behavior in Nano-Porous Materials: Free
    ÍÒÖ×ØÒÒ ÖÞÒ ÚÓÖ Ò ÆÒÓ¹Ô ÓÖÓÙ× ÅØÖÐ× Ö ÒÖ Ý ËÑÙÐØÓÒ ËØÙ× Ò ÜÔ ÖÑÒØ ××ÖØØÓÒ ÈÖ×ÒØ ØÓ Ø ÙÐØÝ Ó Ø Ö ÙØ Ë Ó ÓÐ Ó ÓÖÒÐÐ ÍÒÚÖ×ØÝ Ò ÈÖØÐ ÙЬÐÐÑÒØ Ó Ø ÊÕÙÖÑÒØ× ÓÖ Ø Ö Ó Ó ØÓÖ Ó È ÐÓ×ÓÔ Ý Ý ÊÚ ÊÖ×ÒÒ ÙÙ×Ø ¾¼¼¼ ÊÚ ÊÖ×ÒÒ ¾¼¼¼ ÄÄ ÊÁÀÌË ÊËÊÎ ÍÒÖ×ØÒÒ ÖÞÒ ÚÓÖ Ò ÆÒÓ¹Ô ÓÖÓÙ× ÅØÖÐ× Ö ÒÖÝ ËÑÙÐØÓÒ ËØÙ× Ò ÜÔ ÖÑÒØ ÊÚ ÊÖ×ÒÒ¸ Ⱥº ÓÖÒÐÐ ÍÒÚÖ×ØÝ ¾¼¼¼ ÍÒÖ×ØÒÒ Ô× ÚÓÖ Ò ÓÒ¬Ò ×Ý×ØÑ× × ØÖÑÒÓÙ× Ô ÓØÒØÐ Ò ÑÔÖÓÚÒ Ø Æ ÓÚÖØÝ Ó ×ÔÖØÓÒ ÔÖÓ ××× ØØ Ù× Ô ÓÖÓÙ× Ñ¹ ØÖÐ× Ð ØÚØ Ö ÓÒ׸ ÓÒØÖÓÐÐ Ð××׸ ×Ð ÜÖÓÐ× ² ÖÓÐ׸ Ö ÓÒ ÖÓÐ× Ò ÞÓÐØ׺ Ì «Ø× Ó Ø ÖÙ ÑÒ×ÓÒÐØÝ Ò ÒÒ ÒÖ¹ Ø ÒØÖØÓÒ× Ù ØÓ Ø ÔÓÖÓÙ× ×ÙÖ Ú ÑÔ ÓÖØÒØ ÓÒ×ÕÙÒ× ØØ Ò ÓÒÐÝ ÔØÙÖ Ý ÑÓÐÙÐÖ ÐÚÐ ÑÓ ÐÒº ÆÓÚÐ Ô× ØÖÒ×ØÓÒ× Ò Ö×ÙÐØ ´ÔÐÐÖÝ ÓÒÒ×ØÓÒ Ò ÕÙ×¹ÓÒ¹ÑÒ×ÓÒÐ ×Ý×ØÑ× Ò ÓÖÒØØÓÒÐ ÓÖÖÒ ØÖÒ×ØÓÒ× Ò ÕÙ×¹ØÛÓ¹ÑÒ×ÓÒÐ ×Ý×ØÑ×µ ØØ ÓØÒ Ö Ø Ù× Ó Ø Ö¹ ÓÛÒ Ó ÑÖÓ×ÓÔ ÕÙØÓÒ× Ð ÃÐÚÒ Ò ×¹ÌÓÑ×ÓÒ ÕÙØÓÒ× × ÓÒ Ð××Ð ØÖÑÓ ÝÒÑ׺ ÁÒ Ø× ÛÓÖ¸ Ø Ó Ù× ÓÒ Ö ÒÖÝ ÑØÓ × ÓÒ ÄÒÙ ØÓÖÝ Û Û ÚÐÓÔ Ò ÔÔÐØÓÒ× Ó Ø× ØÓÖÝ ØÓ ÙÒÖ×ØÒ Ø ÖÓÛÒ Ó Ø ÑÖÓ×ÓÔ ÕÙØÓÒ׸ ÚÐÓÔÒ ÐÓÐ Ô× ÖÑ׸ Ò ÖØÖÞÒ ÜØ Ô×׺ Ì Ö×ÙÐØ× Ó ÓÙÖ ÜÔ ÖÑÒØÐ ×ØÙ× Ö Ð×Ó ×Ö ¸ ØØ ÔÖÓÚ ×ÙÔÔ ÓÖØÒ ÚÒ ÓÖ ÓÙÖ ÑÓ ÐÒ «ÓÖØ׺ ÓÖÔÐ Ë Ø ÓÖÒ Ò Ò Ñ ÑÐÝ Ò ×ÓÙØÖÒ ÁÒ¸ Á Û× ÒØÖ×Ø Ò Ö×Ö ×Ò Ø Ý× Á Ò³Ø ÚÒ ÖÑÑÖº Á ÓÙÒ ÑÝ×Ð ´ÖØÖ ÓÖØÙÒØÐÝ ÓÖ Ñµ ×ØÙÝÒ ÑÐ ÒÒÖÒ Ò Ø ÁÒÒ ÁÒ×ØØÙØ Ó ÌÒÓÐÓÝ Ø ÅÖ׺ ÙÖÒ ÑÝ Ö×ÑÒ ÝÖ Á Û× ×ØÖÙ Ý Ø ÖÐÞØÓÒ ØØ Á Ñ ÒÓ ÐÓÒÖ Ø ÒÓÛ¹ÐÐ Ô Ö×ÓÒ Ò ×Ó Óи ØØ Ø ÛÓÖÐ × ÙÐÐ Ó ÔÝ×Ð ´Ò Ñе ÔÒÓÑÒ ØØ Á ÖÐÝ ÒÛ ÓÙغ Ø Ø ÒÒÒ Ó ÑÝÂÙÒÓÖÝÖ¸ Á ×ØÖØ ØÓ ÚÐÓÔ Ò ÒØÒ× ×ÒØÓÒ ÓÖ ×ØØ×ØÐ ÑÒ× Ò Ò ÑÝ ÑÒ ØÓ ÕÙØ ÑÐ ÒÒÖÒ Ò Ø ÙÔ ÔÝ×׺ ÁØ Û× Ô× ÛÖ Á Û× ÑÒ Ø ÓÒØÒØ× Ó ÑÒÝ Ó Ó× ÓÒ ×ØØ×ØÐ ÔÝ×׸ ÛÒ Á Ñ ÖÓ×× Ø ÓÓ ÅÓÐÙÐÖ ÌÖÑÓ ÝÒÑ× Ó ÐÙ È× ÕÙÐÖ Ý ÂÓÒ ÈÖÙ×ÒØÞº Ì× Û× ØÙÖÒÒ
    [Show full text]
  • Freezing Convenience Foods Include: • You Prepare Food When You Have Time
    FreezingFreezing convenienceconvenience foodsfoods that you’ve prepared at home PNW 296 By C. Raab and N. Oehler our freezer can help you prepare for busy days • You can save money by making convenience foods ahead, parties, or unexpected company. By yourself. planning a steady flow of main dishes, baked Y On the other hand: goods, desserts, and other foods, you can make good • Freezing is expensive when you total the cost of use of your freezer and your time. packaging, energy use, and the freezer itself. Benefits of freezing convenience foods include: • You prepare food when you have time. • You use more energy to cook, freeze, and reheat a dish than you would use to cook it for immediate • You use your oven more efficiently by baking more consumption. than one dish at a time. • Prepared foods have a relatively short storage life • You avoid waste by freezing leftovers to use as compared to the storage life of their ingredients “planned overs.” (such as frozen fruits, vegetables, and meat). • You can prepare special diet foods and baby foods in • Unless you have a microwave, you must allow quantity and freeze them in single portions. plenty of time for thawing. • You save time by doubling or tripling recipes and • Some products don’t freeze well. Others don’t justify freezing the extra food. the labor and expense of freezing. • If you normally cook for just one or two, you can freeze individual portions of an ordinary recipe for later use. A Pacific Northwest Extension Publication Oregon State University • Washington State University • University of Idaho Contents • Use moisture-vapor-resistant packaging such as plas- Preparing foods for freezing .......................................2 tic containers, freezer bags, heavy-duty aluminum Freezer storage ............................................................2 foil, and coated freezer paper to preserve the quality From the freezer to the table .......................................3 of frozen food.
    [Show full text]
  • Notes for States of Matter/Boiling, Melting and Freezing Points/ and Changes in Matter
    Notes for States of Matter/Boiling, Melting and Freezing Points/ and Changes in Matter Matter can be described as anything that takes up space and has mass. There are three states of matter: solid, liquid, and gas. Solids have a definite shape and volume. The particles are tightly packed and move very slowly. Liquids have a definite volume but take the shape of the container they are in. The particles are farther apart. The particles move and slide past each other. Gases have no volume or shape. The particles move freely and rapidly. The boiling, freezing and melting points are constant for each type of matter. For water, the boiling point is 100°C/ freezing and melting points are 0°C. Adding salt to water decreases the freezing point of water. That is why salt is put on icy roads in the winter or why salt is added to an old-fashioned ice cream maker. Adding salt to water increases the boiling point of water. States of matter can be changed by adding or lessening heat. When a substance is heated, the particles move rapidly. Heated solid turns into liquid and heated liquid turns into gas. Removing heat (cooling) turns gas into liquid and turns liquid into solid. Evaporation happens when a substances is heated. Condensation happens when a substance is cooled. Notes for States of Matter/Boiling, Melting and Freezing Points/ and Changes in Matter Matter can be described as anything that takes up space and has mass. There are three states of matter: solid, liquid, and gas. Solids have a definite shape and volume.
    [Show full text]
  • Molal Freezing Point Depression Constants SCIENTIFIC Calculating Kf Values
    Molal Freezing Point Depression Constants SCIENTIFIC Calculating Kf Values Introduction The freezing point of a liquid is the temperature at which the forces of attraction among molecules are just enough to cause a phase change from the liquid state to the solid state. It is the temperature at which the liquid and solid phases exist in equilib- rium. The solvent molecules in a solution are somewhat more separated from each other than they are in a pure solvent due to the interference of solute particles. Therefore, the temperature of a solution must be lowered below the freezing point of the pure solvent in order to freeze it. The freezing point depression (∆Tf) of solutions of nonelectrolytes has been found to be equal to the molality (m) of the solute times a proportionality constant called the molal freezing point depression constant (Kf). Therefore, ∆Tf = Kf × m, Equation 1 where m is the number of moles of solute per kilograms of solvent. Concepts • Freezing point depression • Colligative properties Discussion The determination of the molecular mass of a substance from the freezing point depression is included in many high school and most college laboratory manuals. In a typical experiment, the freezing point of the pure solvent is measured followed by the freezing point of a solution of known molality. Dividing the freezing point depression (∆Tf) by the solution molality (m) gives the molal freezing point constant (Kf) of the solvent, according to Equation 1. The second part of the lab consists of using the Kf value determined in part one to determine the molality, and ultimately the molecular mass of an unknown substance.
    [Show full text]
  • Why Do Substances Have Specific Melting and Freezing Points?
    Melting and Freezing Points Why Do Substances Have Specific Melting and Freezing Points? Lab Handout Lab 9. Melting and Freezing Points: Why Do Substances Have Specific Melting and Freezing Points? Introduction All molecules are constantly in motion, so they have kinetic energy. The amount of kinetic energy a molecule has depends on its velocity and its mass. Temperature is a measure of the average kinetic energy of all the molecules found within a substance. The temperature of a substance, as a result, will go up when the average kinetic energy of the molecules found within that substance increases, and the temperature of a substance will go down when the average kinetic energy of these molecules decreases. Temperature is therefore a useful way to measure how energy moves into, through, or out of a substance. A substance will change state when enough energy transfers into or out of it. For example, when a solid gains enough energy from its surroundings, it will change into a liquid. This process is called melting. Melting is an endothermic process because the substance absorbs energy. The opposite occurs when a substance changes from a liquid to a solid (i.e., freezing). When a liquid substance releases enough energy into its surroundings, it will turn into a solid. Freezing is therefore an exothermic process because the substance releases energy. All substances have a specific melting point and a specificfreezing point. The melting point is the temperature at which a substance transitions from a solid to a liquid. The freezing point is the temperature at which a substance transitions from a liquid to a solid.
    [Show full text]
  • CHAPTER 3 Freezing and Thawing of Foods – Computation Methods And
    CHAPTER 3 Freezing and thawing of foods – computation methods and thermal properties correlation H. Schwartzberg1, R.P. Singh2 & A. Sarkar2 1Department of Food Science, University of Massachusetts, USA. 2Department of Biological and Agricultural Engineering, University of California – Davis, USA. Abstract Correlations are derived for local water activities, aw, unfrozen water contents, nw, ice contents, nI, effective heat capacities, C, thermal conductivities, k, and specific enthalpies, H, as functions of temperature, T, in foods at subfreezing conditions.The validity of the correlations has been demonstrated for many foods. The correlations can be used to provide thermal properties data for freezing and thawing calculations, including numerical solution of partial differential equations (PDEs) describing heat transfer during freezing and thawing. Finite element and finite difference methods for solving such PDEs are described, particularly enthalpy step methods. Local T versus time, t, histories for food freezing and thawing obtained by the use of these methods are presented. 1 Engineering calculations Food process engineers often have to calculate heat transfer loads for freezing and thawing, how fast such heat can be transferred, how changing product or process variables affects transfer rapidity, how freezing rates and T differ in different parts of a product, and how T rises in frozen food exposed to abusive conditions. Thermal property correlations and computational methods presented here can be used for such calculations. 2 Freezing points Pure water and normal ice, i.e. ice Ih, are in equilibrium at temperature To (273.16K, 0◦C, or 32◦F) at atmospheric pressure. This chapter deals with freezing WIT Transactions on State of the Art in Science and Engineering, Vol 13, © 2007 WIT Press www.witpress.com, ISSN 1755-8336 (on-line) doi:10.2495/978-1-85312-932-2/03 62 Heat Transfer in Food Processing and thawing of normal ice in foods.
    [Show full text]
  • 3.3 Definitions & Notes PHASE CHANGES
    3.3 Definitions & Notes PHASE CHANGES WORDS FOR DEFINITIONS YOU NEED ARE IN RED Phase Heat of Heat of Endothermic exothermic change fusion vaporization vaporization Evaporation Vapor condensation sublimation pressure deposition PHASE CHANGE: thermal energy (HEAT) is transferred to or from a substance that causes a change in phase. During a phase change the temperature of the substance does not change A phase change is reversible ( can be undone or the substance can be returned to its original state) Phase change is a physical change, NOT A CHEMICAL CHANGE. Why doesn’t temperature change during a phase change? The thermal energy is consumed while breaking bonds. EXAMPLES: Ice absorbs heat to melt to liquid water. Liquid water gives off heat and freezes. TRANSITION: when a substance is moving from one phase to another it is in TRANSITION As a verb “ A substance is transitioning” – changing. EXO THERMIC: when heat is given off (Ex means – outside) ENDO THERMRIC: when heat is taken in THE TRANSITIONS WE ALREADY KNOW TRANSITION Description The transition from solid to liquid Melting Heat is absorbed by substance or added to substance The transition from liquid to solid Freezing Heat is given off by substance or absorbed by the surroundings The transition from Gas to liquid Condensation Heat is given off by substance or absorbed by the surroundings The transition from Liquid to Gas AT the Boiling point Vaporization Heat is absorbed by substance or added to substance The transition from Liquid to Gas BELOW the Boiling Evaporation point Heat is absorbed by substance or added to substance THE TRANSITIONS WE MAY NOT ALREADY KNOW TRANSITION Description The transition from solid directly to gas SUBLIMATION Heat is absorbed by substance or added to substance Example? The transition from gas directly to solid DEPOSITION Heat is given off by the substance or taken away Example? Data from Melting/Freezing Lab done with Napthalene TEMPERATURE CHANGING Do I need to write this down? Write down what you need.
    [Show full text]