Question

Classify the following substance as element, compound or mixture:

Iodised salt

Answer 1

Iodised salt can be classified as a mixture.

• Iodised salt contains two substances i.e.; salt or common salt or Sodium chloride $\left(\mathrm{NaCl}\right)$ and Iodine $\left({\mathrm{I}}_2\right)$.
• Iodine is generally present in the form of some Iodine compound such as Potassium iodate $\left({\mathrm{KIO}}_3\right)$
• Therefore, it is a mixture of a compound (common salt) and an element (Iodine).

Element: An element is a pure substance that cannot be split into simpler substances.

• Example: Hydrogen $\left(\mathrm{H}\right)$, Copper $\left(\mathrm{Cu}\right)$ etc.

Compound: A compound is a pure substance in which elements combine chemically in a fixed composition to give a compound.

• They can be broken down into elements that make up the compound by using chemical or electrochemical methods.
• The properties of the compound are entirely different from the elements from which it is formed.
• Example: Water $\left({\mathrm{H}}_2\mathrm{O}\right)$, Common salt i.e.; Sodium chloride $\left(\mathrm{NaCl}\right)$

Mixture: When two or more substances (elements or compounds or an element and compound) are mixed in any proportion.

• The components of a mixture can be separated by physical methods of separation.
• Example: A mixture of Sand and Iron $\left(\mathrm{Fe}\right)$ can be separated by using a magnet (physical process) where Iron gets attracted to the magnet leaving behind sand.