Classification of Chemical Substance

Topics: Electrical resistance, Molecule, Chemistry Pages: 3 (786 words) Published: May 3, 2012
Chemistry Laboratory Report

Classification of Chemical Substances

Student: Saule Sadykova
Lab Partner #1: Temirlan Atambaev
Lab Partner #2: Almas Ospanbekov
Instructor: Eugene Douglass

Nazarbayev University
Purpose
The aim of this experiment is to investigate the properties of several substances with the purpose of determining whether they are molecular, ionic, macromolecular or metallic. Introduction
Chemical substances could be named ionic, molecular or metallic substance, based on the kind of bond present in it. Solid ionic compound is composed of ions, which are held together by large electrostatic forces. Bonding in molecular substance is caused by the sharing of electrons by atoms. When the stable aggregates resulting from covalent bonding contain relatively small numbers of atoms, they are called molecules, if aggregates are very large and include essentially all the atoms in a macroscopic particle, it is called macromolecular. Bonding in metallic substances is caused by the free movement of electrons. Materials

Test tubes, Bunsen burner, distilled water, thermometer, portable ohmmeter, penny, rubber washer, pliers Procedure
a. Melting Point
A pea-size sample of a substance is taken. If the sample melts between 100° and 300° C, it will take more than gentle warming, but will melt before the test tube turns the flame of Bunsen burner to yellow-orange color. Above 300° C, there will be increasing color; up to about 500° C one can still use a test tube and a strong burner flame; however in this experiment there will not be measured any m.p. which are above 500oC. Sample is heated, with a loosely closed stopper. During the heating process, sample is observed in order to reveal decomposition, sublimation, or evolution of water. b. Solubility and Conductance of Solutions

Sample is placed in a regular size test-tube with 2 mL of solvent and stirred. It can dissolve immediately, partially, remain the same or produce a cloudy suspension....
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