Vernier Software and Technology
Vernier Software & Technology

Determining Melting Temperature

Introduction

The melting temperature of a compound is the temperature at which it changes from a solid to a liquid. This is a physical property often used to help identify compounds or to check the purity of a compound. The melting temperature is related to the amount of kinetic energy that one adds to a solid substance to overcome the intermolecular attractions that maintain its solid state under given conditions.

It is very difficult, however, to find an exact melting point. Because it is a thermodynamic process, when a substance begins to melt, a dynamic equilibrium is established within which the substance exists in both solid and liquid form. Because the energy transferred to this system is not used entirely to convert the solid to a liquid, a single temperature value is commonly not reported, but rather a temperature range.

Thus, melting temperatures are usually reported as values with a range of 2–3°C. Melting temperature is not a unique physical property of a substance, but it does help you understand more about the substance. It can also help determine the purity of a substance that you have synthesized.

You will use a Vernier Melt Station to determine the melting temperature of a solid substance. Your sample will be one of several possible pure compounds. Your first trial will help you narrow your possibilities. On subsequent trials you will be able to accurately determine the melting temperature of your sample, thus identifying the compound.

Objectives

In this experiment, you will

  • Prepare a solid substance for measuring melting temperature.
  • Measure the temperature of a solid substance as it warms to melting.
  • Analyze the temperature vs. time graphs to determine the rate of heating and the melting temperature of a sample of a solid organic compound.
  • Identify the solid from a list of possible pure compounds.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Organic Chemistry with Vernier

See other experiments from the lab book.

1Determining Melting Temperature
2Recrystallization
3Determination of a Boiling Point
4Identifying an Unknown Analgesic by Three Methods
5Separation of Organic Compounds by Acid-Base Extraction Techniques
6Understanding Polarimetry
7Identification of Organic Unknowns Using Polarimetry
8Investigating Gas Chromatography
9Fractional Distillation of Esters
10Understanding Intermolecular Forces Using a Gas Chromatograph: Enthalpy of Vaporization
11Investigating Thermodynamic Relationships of Substituted Hydrocarbons
12Extraction of Spinach Pigments and Analysis by Electronic Absorption Spectroscopy
13SN1: Synthesis of t-butyl chloride
14SN2: Synthesis of 1-bromobutane
15Observing the Reaction Kinetics of Sucrose with Polarimetry
16The Synthesis and Analysis of Aspirin
17Isolation of R-(+)-Limonene from Oranges using Steam Distillation
18Synthesizing Ethyl Acetate by Fisher Esterification
19Synthesis of Dibenzalacetone by Aldol Condensation
20The Diels-Alder Reaction of Anthracene with Maleic Anhydride
21Friedel-Crafts Acylation of Ferrocene
22Grignard Formation of Crystal Violet
23Synthesis of Fluorescein
24Synthesis of Methyl Orange and Its Application to Textiles
25Analysis of Natural Products
26Using a Gas Chromatograph: Identifying an Unknown Compound

Experiment 1 from Organic Chemistry with Vernier Lab Book

<i>Organic Chemistry with Vernier</i> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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