SepMix - Separation of a Mixture Objective: The purpose of...

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Separation of a Mixture Objective: The purpose of this experiment is to separate a mixture of sand and salt on the basis of differences in physical properties to determine the percent by mass of each of these compounds in the mixture. Safety Tips: Wear safety goggles at all times in the laboratory. Background: Any material that is made up of at least two or more substances that are not chemically combined is a mixture. Mixtures are not unique to chemistry; we use and consume them daily. The fuel used in vehicles, the beverages we consume every day, and the ground we walk on are all examples of mixtures. The separation of mixtures into their components is of great commercial value, as well as a necessary step in the isolation of a pure compound in the chemical laboratory. An example of this is the separation of crude oil and gasoline. Each component in a mixture keeps its own set of physical properties. These differences in physical properties will be used to separate a mixture of salt (sodium chloride, NaCl) and sand (silicon dioxide, SiO 2 ) in this laboratory exercise. Techniques have been developed by chemists for the separation of mixtures and several of these techniques are outlined below. Solubility A solution is a homogeneous mixture of two or more substances. A solution is composed of a solute and a solvent. A solute is the chemical substance that is being dissolved and generally the substance that is present in the smaller amount. The solvent is the chemical substance that is doing the dissolving and generally the substance that is present in the greater amount. Solubility is defined as the maximum amount of solute that will dissolve in a fixed amount of solvent at a given temperature. Commonly the units are grams of solute per 100 grams of solvent. Many factors affect the solubility of a solute. A major factor is the chemical nature of the solvent and the solute. As a rule, "like will dissolve like": polar solvents will dissolve polar solutes, and nonpolar solvents will dissolve nonpolar solutes. Polar is a term applied to covalent bonds and molecules when the center of positive charge and the center of negative charge do not coincide, thus forming an electric dipole. Nonpolar bonds and molecules do not possess a dipole moment. For example, polar compounds, such as sugar and alcohols, and ionic compounds, such as potassium
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SepMix - Separation of a Mixture Objective: The purpose of...

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