Question

2. A physical property can be used to identify a substance; however, differences in physical properties can also be used to separate one substance from another. Explain how the following properties can be used to either identify or separate the following:
   a.Solubility of sodium chloride and silicon dioxide b.Melting point of naphthalene and water

Answer 1

One practical application of chemistry is that it can be used to help separate one substance from another. The reasons materials may be separated from each other is because there is some difference between them, such as size, state of matter, solubility , electrical charge, or melting point

(a). SEPARATING SALT AND SAND USING SOLUBILITY

One method of separating salt and sand is based on solubility. If a substance is soluble it means it dissolves in a solvent. Salt (sodium chloride) is an ionic compound that is soluble in water. Sand (mostly silicon dioxide) is not.

b) SEPARATING A MIXTURE OF NAPHTHALENE AND WATER USING MELTING POINT

The melting point of naphthalene is .C . The melting point of water is C. Naphthalene have very high melting point, so to separate them, just cool the mixture down to room temperature ( actually any temperature below 80 degree is fine) wait for the naphthalene to completely solidify and finally filter it out using filter paper