Question

Classify the following substance into elements, compounds and mixtures:

Marble

Answer 1

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

• Example: Hydrogen $\left({\mathrm{H}}_2\right)$, 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 the use of a magnet (physical process) where Iron gets attracted to the magnet leaving behind the sand.

Marble i.e.; Calcium carbonate $\left({\mathrm{CaCO}}_3\right)$ can be classified as a compound.

• This is because marble is made up of three elements combined chemically i.e.; Calcium$\left(\mathrm{Ca}\right)$, Carbon$\left(\mathrm{C}\right)$ , and Oxygen $\left(\mathrm{O}\right)$ in a definite composition of 1:1:3.
• In the sense that marble contains only one type of constituent particles which have identical chemical properties i.e.; $\left({\mathrm{CaCO}}_3\right)$ particles, it is a pure substance.
• The properties of the compound (marble) are different from the elements it is made up of.
• Marble can be broken down into its elements by chemical methods only that can break the bonds between its elements.