Explain the term 'phase' with appropriate examples.
1. PHASE: A phase is defined as any homogenous I physically distinct and mechanically separable portion of a system I which is separated from other parts of the system by de finite surface. Example:-
• In a freezing water system ice, water and water vapour are the three phases which are physically distinct and homogenous.
• A gaseous mixture which is thoroughly miscible in all proportion consists of a single phase.
• If two liquids are miscible they will form one liquid phase only.
• Thermal decomposition of CaC03 consists of three phases namely, two solids and one gaseous.
• A mixture of CaO and CaC03 consists of two phases.
• Two immiscible liquids like water and oil will form two separate phases.