Solutions are a special kind of mixture. Solubility is a term used to describe the amount of materials (solids, liquids, or gas) which can be dissolved in a solvent to make a solution. The research aspect of this science fair project is to test the solubility of several common liquid substances. What are the goals? Several common liquids, such as water, rubbing alcohol, and club soda, will have solids such as salts, sand, and baking soda added to them to determine which solids dissolve in which liquids at room temperature. Based on the results of this investigation a data table will be prepared and the results potted on a series of graphs. A rule of thumb for solubility in solvents is "like dissolves like." This means that in general, polar compounds are soluble in polar solvents and non-polar compounds are soluble in non-polar solvents. One practical benefit of the results of this project is to prove or disprove this rule.
Solutions are a special kind of mixture. Solubility is a term used to describe the amount of materials (solids, liquids, or gas) which can be dissolved in a solvent to make a solution. A solvent is the dissolving agent, e.g. water. A solute is a substance that is dissolved in a solution. In this science fair project, solutions in which the solvent is a liquid will be investigated. Most liquid solvents are molecular compounds. Whether a compound will dissolve in a particular solvent depends on what that solvent is. The rule of thumb for solubility in molecular solvents is "like dissolves like." This means that in general, polar compounds (chemical compounds whose molecules exhibit electrically positive characteristics at one extremity and negative characteristics at the other) are soluble in polar solvents and non-polar compounds are soluble in nonpolar solvents. Water is an example of a polar solvent. Cooking oil is an example of a nonpolar solvent. Water is the most commonly used liquid solvent. It is sometimes called the "universal solvent" because it can dissolve more substances than any other liquid. What materials are required? Rubbing alcohol, club soda, cooking oil, table salt, baking soda, table sugar, Epsom salt, package of plastic drinking cups, coffee stirrers, metric measuring cup, clean playground or beach sand, and rubber or Latex disposable gloves Where can the materials be found? All of the items for this project can be a purchased locally at most major retail stores (Walmart, Target, dollar stores, etc).
Terms/Concepts: Solution; solubility; solvent; solute; polar compound References: References to related books Title: Janice VanCleave's Chemistry for Every Kid: 101 Easy Experiments that Really Work Author: Janice VanCleave Publisher: Jossey-Bass. Inc. ISBN-10: 0471620858 and ISBN-13: 978-0471620853 This book contains many experiments design to be conducted by elementary and middle school science age children. It also explains basic chemistry concepts that will be useful in conducting this science fair project. Links to related sites on the web Title: Solubility of Salts URL: http://www.elmhurst.edu/~chm/vchembook/171solublesalts.html Title: What is Solubility? URL: http://www.chemistryland.com/CHM107/Water/WaterTutorial.htm NOTE: The Internet is dynamic; websites cited are subject to change without warning or notice! Disclaimer and Safety Precautions Education.com provides the Science Fair Project Ideas for informational purposes only. Education.com does not make any guarantee or representation regarding the Science Fair Project Ideas and is not responsible or liable for any loss or damage, directly or indirectly, caused by your use of such information. By accessing the Science Fair Project Ideas, you waive and renounce any claims against Education.com that arise thereof. In addition, your access to Education.com's website and Science Fair Project Ideas is covered by Education.com's Privacy Policy and site Terms of Use, which include limitations on Education.com's liability. Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.
What occurs at the molecular level to cause a solute to dissolve in a solvent? The answer depends in part on the strength of attractions between solute and solvent particles. A good rule of thumb is to use is like dissolves like, which means that substances must have similar intermolecular forces to form solutions. A substance can dissolve in a solvent, and form a solution, if the solute and solvent are attracted to each other. For example, water molecules that are held together by hydrogen bonding will dissolve solutes that can also hydrogen bond, like ethanol (CH3CH2OH). The new hydrogen bonds between the water and the ethanol molecules (solvent-solute attractions) are nearly as strong as the hydrogen bonds in water (solvent-solvent) and ethanol (solute-solute) alone, making the process of solution formation (also called dissolution or dissolving) favorable. In the case of a solid or liquid solute, the interactions between the solute particles and the solvent particles are so strong that the individual solute particles separate from each other and, surrounded by solvent molecules. (Gaseous solutes already have their constituent particles separated, but the concept of being surrounded by solvent particles still applies.) This process is called solvation and is illustrated in Figure \(\PageIndex{1}\). When the solvent is water, the word hydration, rather than solvation, is used. When a solute and solvent that do not have similar intermolecular forces are mixed, a solution is not formed because the solute-solute or solvent-solvent attractions are stronger than any favorable interactions between solute and solvent. For example when water and oil are mixed, they will stay in separate layers: the water molecules remain hydrogen bonded to each other and the oil molecules stay together.
In the case of molecular solutes like glucose, the solute particles are individual molecules. However, if the solute is ionic, the individual ions separate from each other and become surrounded by solvent particles. The positively charged cations are attracted to the neg and anions of an ionic solute separate when the solute dissolves. This process is referred to as dissociation (Figure \(\PageIndex{1}\)). The dissociation of soluble ionic compounds gives solutions of these compounds an interesting property: they conduct electricity. Because of this property, soluble ionic compounds are referred to as electrolytes. Many ionic compounds dissociate completely and are therefore called strong electrolytes. Sodium chloride is an example of a strong electrolyte. Some compounds dissolve but dissociate only partially, and solutions of such solutes may conduct electricity only weakly. These solutes are called weak electrolytes. Acetic acid (CH3COOH), the compound in vinegar, is a weak electrolyte. Solutes that dissolve into individual neutral molecules without dissociation do not impart additional electrical conductivity to their solutions and are called nonelectrolytes. Table sugar (C12H22O11) is an example of a nonelectrolyte.
The following substances all dissolve to some extent in water. Classify each as an electrolyte or a nonelectrolyte.
Each substance can be classified as an ionic solute or a nonionic solute. Ionic solutes are electrolytes, and nonionic solutes are nonelectrolytes.
The following substances all dissolve to some extent in water. Classify each as an electrolyte or a nonelectrolyte.
a. nonelectrolyte b. electrolyte c. nonelectrolyte d. electrolyte
Our body fluids are solutions of electrolytes and many other things. The combination of blood and the circulatory system is the river of life, because it coordinates all the life functions. When the heart stops pumping in a heart attack, the life ends quickly. Getting the heart restarted as soon as one can is crucial in order to maintain life. The primary electrolytes required in the body fluid are cations (of calcium, potassium, sodium, and magnesium) and anions (of chloride, carbonates, aminoacetates, phosphates, and iodide). These are nutritionally called macrominerals. Electrolyte balance is crucial to many body functions. Here's some extreme examples of what can happen with an imbalance of electrolytes: elevated potassium levels may result in cardiac arrhythmias; decreased extracellular potassium produces paralysis; excessive extracellular sodium causes fluid retention; and decreased plasma calcium and magnesium can produce muscle spasms of the extremities. When a patient is dehydrated, a carefully prepared (commercially available) electrolyte solution is required to maintain health and well being. In terms of child health, oral electrolyte is given when a child is dehydrated due to diarrhea. The use of oral electrolyte maintenance solutions, which is responsible for saving millions of lives worldwide over the last 25 years, is one of the most important medical advances in protecting the health of children in the century, explains Juilus G.K. Goepp, MD, assistant director of the Pediatric Emergency Department of the Children's Center at Johns Hopkins Hospital. If a parent provides an oral electrolyte maintenance solution at the very start of the illness, dehydration can be prevented. The functionality of electrolyte solutions is related to their properties, and interest in electrolyte solutions goes far beyond chemistry. Sports drinks are designed to rehydrate the body after excessive fluid depletion. Electrolytes in particular promote normal rehydration to prevent fatigue during physical exertion. Are they a good choice for achieving the recommended fluid intake? Are they performance and endurance enhancers like they claim? Who should drink them? Typically, eight ounces of a sports drink provides between fifty and eighty calories and 14 to 17 grams of carbohydrate, mostly in the form of simple sugars. Sodium and potassium are the most commonly included electrolytes in sports drinks, with the levels of these in sports drinks being highly variable. The American College of Sports Medicine says a sports drink should contain 125 milligrams of sodium per 8 ounces as it is helpful in replenishing some of the sodium lost in sweat and promotes fluid uptake in the small intestine, improving hydration.
In the summer of 1965, the assistant football coach of the University of Florida Gators requested scientists affiliated with the university study why the withering heat of Florida caused so many heat-related illnesses in football players and provide a solution to increase athletic performance and recovery post-training or game. The discovery was that inadequate replenishment of fluids, carbohydrates, and electrolytes was the reason for the “wilting” of their football players. Based on their research, the scientists concocted a drink for the football players containing water, carbohydrates, and electrolytes and called it “Gatorade.” In the next football season the Gators were nine and two and won the Orange Bowl. The Gators’ success launched the sports-drink industry, which is now a multibillion-dollar industry that is still dominated by Gatorade.University of Florida football player Chip Hinton testing Gatorade in 1965, pictured next to the leader of its team of inventors, Robert Cade. Concept Review Exercise
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5. 6. a. no b. no c. no d. yes |