Aim
The aim of this experiment is to classify some unknown substances as metallic, ionic, or covalent using physical and chemical tests, allowing for a better understanding of the properties and characteristics of different substance types.
Introduction
In this experiment, you will be provided with eight samples of unknown substances, and your task is to devise a simple set of tests to identify the different substances based on their properties.
The suggested sample set includes sugar, sodium chloride, sodium thiosulphate, a gas jar of oxygen, distilled water, ethanol, magnesium powder, and iron powder. By observing the appearance, boiling point, conductivity, solubility, and reaction with dilute hydrochloric acid, you can determine whether each substance is metallic, ionic, or covalent in nature.
Requirements
safety glasses 6 test-tubes in a rack 6 ignition tubes test-tube holder Bunsen burner and protective mat (note: the maximum temperature for most Bunsen burners is 800°C) beaker, 100 cm³ battery and lamp in holder 2 carbon electrodes 3 connecting leads with crocodile clips unknown substances, in bottles labeled A-H
Experimental Procedure
- Observe the appearance of each sample and record your observations in the results table.
- Estimate the boiling point of each sample by heating it gently in a test tube or ignition tube using a Bunsen burner.
- Test the conductivity of each solid sample using a battery, lamp, and carbon electrodes connected with crocodile clips.
- Test the solubility of each sample in water by mixing a small amount with distilled water in a test tube.
- Test the conductivity of each sample’s solution (if soluble) using the same setup as in step 3.
- Observe the action of dilute hydrochloric acid on each sample by adding a few drops to a small amount of the sample in a test tube.
- Based on the results of the tests, classify each substance as metallic, ionic, or covalent.
Results Table
| Sample A | Sample B | Sample C | Sample D | Sample E | Sample F | Sample G | Sample H | |
|---|---|---|---|---|---|---|---|---|
| Appearance | ||||||||
| Boiling-point | ||||||||
| Conductivity (solid) | ||||||||
| Solubility (water) | ||||||||
| Conductivity (solution) | ||||||||
| Action of HCl(aq) | ||||||||
| Structure |
Questions
- What further tests would probably help to identify the structures which you could not identify in the experiment?
- Why is it more difficult to recognize a powdered metal than a solid lump?
Practical Science 
What substance do you recommend using for this practical activity?
The suggested sample set includes sugar, sodium chloride, sodium thiosulphate, a gas jar of oxygen, distilled water, ethanol, magnesium powder, and iron powder.