How do you test for the purity of a prepared salt?

You can test the purity of a prepared salt by checking its melting point or boiling point, or through chromatography.

The purity of a prepared salt can be determined using several methods. One of the most common methods is by checking its melting point or boiling point. Pure substances have specific melting and boiling points. If the salt is pure, it will melt or boil at a specific temperature. If it contains impurities, the melting or boiling point will be lower or higher than the expected value. This is because impurities disrupt the regular arrangement of particles in the substance, which affects the amount of energy required to change its state.

Another method is through chromatography, a technique used to separate the different components in a mixture. In this process, the salt is dissolved in a suitable solvent and the solution is allowed to travel up a piece of chromatography paper. The different components in the salt will travel at different rates, resulting in a series of spots on the paper. If the salt is pure, there will only be one spot. If there are impurities, multiple spots will be visible.

It's also possible to use a technique called spectroscopy, which involves shining a light through the salt and analysing the spectrum of light that comes out the other side. Different substances absorb and emit light at different wavelengths, so by studying the spectrum, you can determine what substances are present in the salt.

Remember, these tests can only indicate the presence of impurities, they cannot identify what the impurities are. To identify the impurities, more complex techniques such as mass spectrometry or infrared spectroscopy may be required.