DOCSLIB.ORG

Freezing Point Through Various Experiments, Students Will Investigate the Properties of Water and Find out What Changes It from One State to Another

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Freezing Point Through Various Experiments, Students Will Investigate the Properties of Water and Find out What Changes It from One State to Another Freezing Point Through various experiments, students will investigate the properties of water and find out what changes it from one state to another Grade Level: 4th Grade Next Generation Science Excellence in Environmental Standards Education Guidelines Phenomena: 4-ESS3-2. Generate and compare Strand 2.1— the Earth as a How does water’s chemical multiple solutions to reduce the Physical System. structure change from a liquid impacts of natural Earth processes to solid? on humans. B) Changes in matter— Learners are able to identify Science and Engineering basic characteristics of and Objectives: Practices (SEP): changes in matter. Describe Students will state the Asking questions and defining objects in terms of the materials temperature at which problems. they are made of and their water freezes in both Analyzing and interpreting data. observable properties. Identify the effects of factors such as Fahrenheit and Celsius Disciplinary Core Ideas: heating, cooling, and moisture Students will explain why 4-LS1 From Molecules to on the properties of materials ice is less dense than Organisms: Structures and and how quickly change water Processes happens. For example, describe Students will evaluate the change of water from solid to Cross Cutting Concepts: liquid to gas in the environment. environmental Energy and matter. implications related to the Stability and change. density of ice. Materials: Ice 4-5 pieces per student Frozen bottle or jug of water Background state. Water is unique because Clear plastic cups it can be observed as a solid, Activity sheet (page 7) Ice plays an important role in liquid, and gas within a our everyday lives, especially relatively small temperature Time Considerations: during the long winter months range. (0-100 °C) Preparations: 20-25 min in northern Nevada. We use it Activity 1: 5-7 min When water cools to 0⁰C Activity 2: 5-7 min in our drinks, it forms on (32⁰F) It begins to solidify. Activity 3: 10 min sidewalks, allows us to skate Activity 4: 15 min on lakes and can ruin our fruit. This process is called freezing, Activity 5: 10 min Understanding the properties so the temperature at which Activity 6: 10 min of ice allows us to better something changes from a understand how it can affect liquid to a solid is called the Related Activities: our daily lives. freezing point. When ice Let it Snow! Let it Melt! warms up to 0⁰C and begins to Like all substances, water can melt that temperature is called exist as a solid, liquid, or gas. the melting point. Ice is the solid form of water while the term water vapor is When many substances freeze used to describe its gaseous the molecules pack together, 1 reducing the amount of empty A simple visual representation of taken up by a set number of space and making the solid this can be done using your molecules. Density can be form more dense than the liquid calculated using density =mass form. However, the shape of ÷ volume (or stuff ÷ space). water molecules causes ice When water freezes it takes up crystals to have more empty more space but no ‘stuff’ is space than liquid water. added. This causes ice to have a lower density than liquid water Water molecules consist of two so ice floats. hydrogen atoms bonded to a This reduced density has a profound effect on the environment. As water in lakes The structure of an ice crystal has more open space than a salt crystal. and ponds freeze, it floats to the surface and creates a layer of fingers. Hold your thumb and ice that insulates the rest of the forefinger into an ‘L’ shape, pond. This prevents the pond roughly modeling the water from freezing solid and allows molecule and the angle. The tip fish to swim around underneath. of your thumb and finger are the Freezing the water contained in hydrogen atoms while the skin fruit can have drastic between them represents the consequences. Plant cells are Atoms in a salt crystal are closely packed oxygen. filled with liquid, but have a fixed single oxygen atom. Due to In liquid water, the molecules volume. When the water in cells electronic forces, the molecule are free to slide past each other. freezes it expands and breaks is bent at an angle of 104.5⁰. It To model this, place the web open the cells destroying the is this angle which allows for the between your thumb and fruit. To prevent this from expansion of ice. When water forefinger nearly together and happening, farmers will spray exists in the liquid form, the twist or slide your hands. In their fruit with water in an molecules are free to move water, the molecules move extreme cold so the outside around and bump together. close together like this, yet do freezes. This creates an When the freezing point of a not actually join together. This insulation so the temperature of substance is reached, is due to the hydrogen bonds the fruit will not fall below 32 molecules begin to form bonds constantly being created and degrees, even if the outside with each other creating solid destroyed. temperature keeps decreasing. crystals. In water, a hydrogen Since more than half of the bond forms between the To model ice, connect your thumb or forefinger to the web of human body is water, our cells hydrogen of one molecule and can be damaged by the cold the oxygen of another. Since the your other hand. With your hands connected this way, they too. When human cells are molecules are bent, the forming damaged by freezing it is called of these bonds creates open take up much more space just like the molecules in ice. frostbite and severe cases might space in the crystal causing the require amputation to prevent water to expand as molecules Since water expands when it infection. become fixed in place. freezes, the density is affected. Density is the amount of space Ice also is a huge factor in weathering and the deterioration 2 of roads. When snowmelt or Where do we find ice in the Ask the students to hold up their runoff freezes on a roadway or world? (glaciers, icecaps, arctic, thumb and forefinger in an ‘L’ in a rock, the water that is Antarctica, your freezer, etc) shape. The tips of their thumb trapped in the cracks will and finger represent the expand, causing more cracking What is the process by which hydrogen and the web of skin to occur. This process is called water turns into a solid? between them represents the ice wedging. (freezing) oxygen. The angle is about the same as a water molecule. Prior to the lesson, freeze a At what temperature does this sealed plastic bottle or milk jug occur? (32⁰ For 0⁰ C) Demonstrate how the water filled with water. This temperature is called the molecules are arranged by freezing point, because it is interlocking your two Preparation the point at which liquid water ‘molecules’. turns into solid ice. In any liquid, the molecules Gather all lesson materials. Activity 2: What is Water? move freely and bump into each other. (move your “molecules”) Introduction: Before we can take a closer look at what happens when water At the freezing point, the Begin the lesson by holding up a molecules slow down and bind jug of water that has been freezes, we must understand water a bit more. together. In water, each frozen solid. Ask the students hydrogen bonds with an oxygen. what they notice about the jug. Ask the class what water is. (stick one thumb to the web of (the sides are bulging or broken) (Water molecules, H2O, your other hand) hydrogen and oxygen) Doing the Activity Show the difference between ice Ask the students why they think Write H2O on the board and ask and water a few times with your the sides of the jug are bulging. hands, having the students (Do not give answer, allow follow along. But don’t mention students just to brainstorm that the ice has expanded. ideas). Explain that today we are going to learn about some Activity 3: What is Ice? unique properties of ice that (NOTE: This activity builds off of explain what happened to the the December mineral/crystal jug. lesson for fourth grade). Activity 1: Ice brainstorm Ask the students how many of Ask students to list some things what it means. What does the them think ice is a mineral. they already know about ice. ‘H’ stand for? The ‘O’? What about the ‘2’? (2 hydrogen Ask the students what all The following questions may be minerals have in common and used to help guide discussion: atoms and one oxygen atom) These are the parts of every write these characteristics on What is ice? (the solid form of water molecule. the board: water) Draw the molecule on the board, Non-living (inorganic) What are the other forms water making sure you mark the Naturally occurring can take? (Liquid water, solid angle. ice, gaseous water vapor) 3 Definite crystalline when we place them in water? Tell the students that the structure Why does ice float? temperature is dropping to the freezing point and have them Definite chemical Activity 5: Why Ice Floats or bond by placing one hand gently composition Density on a classmate’s head without With the students, compare Ask the students why the ice is moving their arms. each property to the properties floating. ( it is NOT lighter, it is Ask students to look at the of ice. (ice has all four less dense than the water) amount of space their “ice” properties) Ask the students to hold up their takes up.
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]
  • 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.
    [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]