1) Pure Substances
A pure substance is a material that consists of only one type of particle, either atoms or molecules, and has a consistent and well-defined composition. Pure substances can be either elements or compounds. Elements are the simplest form of matter and cannot be broken down into simpler substances by chemical means. Compounds, on the other hand, are formed when two or more elements chemically combine. Pure substances have a definite and consistent melting point, boiling point, and density.
2) Impure Substances
Impure substances, also known as mixtures, are substances that consist of two or more components that are not chemically bonded to one another. These substances can be either homogeneous or heterogeneous. Homogeneous mixtures have a uniform composition throughout, while heterogeneous mixtures have varying compositions within the substance. Examples of impure substances include alloys, solutions, and suspensions.
Impure substances can be separated through physical processes, such as filtration, evaporation, and distillation, which do not involve any chemical reactions. These processes aim to separate the components of the mixture, resulting in a purer substance.
Differences between Pure and Impure Substances
- Composition: Pure substances have a consistent and well-defined composition, while impure substances have variable compositions due to the presence of multiple components.
- Particle structure: Pure substances consist of only one type of particle, either atoms or molecules, while impure substances contain a mixture of particles.
- Physical properties: Pure substances have consistent and well-defined physical properties, such as melting point, boiling point, and density, whereas impure substances may have varying physical properties due to the presence of different components.
- Chemical composition: Pure substances can be either elements or compounds, while impure substances are mixtures of elements and/or compounds.
- Separation processes: Pure substances cannot be separated into simpler substances by physical means, while impure substances can be separated through physical processes, such as filtration, evaporation, and distillation.
