Separations.pdf - NAME SECTION PARTNER(S DATE SEPARATIONS I...

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Exploring the Chemical World, PGCC, 2003 23 NAME_________________________ SECTION________________ PARTNER(S)___________________ DATE___________________ SEPARATIONS I: BASIC TECHNIQUES This activity is designed to introduce you to a variety of techniques useful for separating mixtures and the reasons why a particular technique is used for a given mixture. By the end of the lab, you will be responsible for determining the most appropriate techniques for mixtures with particular characteristics. PRE-LAB QUERIES 1. You are presented with a container of grey powder. Discuss how you can tell if it is a mixture or a pure substance. 2. Describe how you would accomplish the following separations: a. salt and pepper b. egg white from unbroken egg yolk c. colored beads by color 3. Classify the following as homogeneous or heterogeneous mixtures. ___________________ __________________ ___________________
Exploring the Chemical World, PGCC, 2003 24 INTRODUCTION One characteristic that distinguishes a mixture from a pure substance is the ability to separate the mixture into its components by simple physical means. Whether a mixture is homogeneous or heterogeneous, its components will have properties that can be used to affect this separation . Some of the properties that can aid in the isolation of components are: particle size; color; density; solubility in water; ability to sublime; and magnetism . You will take advantage of these properties during the procedures below. PROCEDURE You will be rotating from station to station in the laboratory to perform each of the separations that follow. For each mixture used you are to record the following information in the data section before you begin that mixture : & detailed physical description of the original mixture; include whether it is homogeneous (same throughout) or heterogeneous; & approach you might take to separate the mixture based on your visual inspection. When you are finished the separation you must record : & description of separated components The stations are numbered 1 through 8. It does not matter in what order you do the stations but you should leave Stations 7 and 8 until you have completed Stations 1-6. The procedure number (below) and the mixture number match the station number. 1a. Obtain one small scoop of Mixture 1 (fine sand, SiO 2 , and table salt, NaCl) and place it in a medium (25mm x 200mm) test tube. What does Mixture 1 look like? After completing the visual inspection, add approximately 5 mL of distilled water to the mixture. Agitate the contents to insure complete mixing. What does this new mixture with the water mixture look like? Has anything happened to the original mixture? Explain. After allowing any material to settle, carefully pour off the water collecting it in a small evaporating dish. Keep the solid component in the test tube. What do you think is the identity of the solid left in the test tube?
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