Question

Classify the following into element, compound, and mixture:

dry ice

Answer 1

Dry ice or solid Carbon dioxide $\left({\mathrm{CO}}_2\right)$ can be classified as a compound because:

• Dry ice is a solid form of Carbon dioxide i.e.; $\left({\mathrm{CO}}_2\right)$ in which two elements Carbon $\left(\mathrm{C}\right)$ and Oxygen $\left(\mathrm{O}\right)$ are present in a fixed ratio by mass In carbon dioxide, one atom of carbon is combined with two atoms of oxygen.
• These elements are in a chemically combined state.
• It can be broken down into smaller components i.e.; carbon and oxygen by chemical methods only.
• The properties of dry ice are different from the properties of its elements i.e.; carbon and oxygen.

It is not an element because it can be broken down into simpler substances.

It is not a mixture because the elements are combined chemically and not physically.

Element: An element is a pure substance that cannot be split into simpler substances and comprises only one type of atom.

• 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.