Chemistry Notes on Concentration, Suspensions, and Colloids PDF

# Concentration of a Solution The concentration of a solution is the amount (mass or volume) of solute present in a given amount (mass or volume) of solution. ## Ways of Expressing Concentration of a Solution - **Mass by mass percentage of solution**: Mass of Solute / Mass of Solution x 100 - **M...

# Concentration of a Solution The concentration of a solution is the amount (mass or volume) of solute present in a given amount (mass or volume) of solution. ## Ways of Expressing Concentration of a Solution - **Mass by mass percentage of solution**: Mass of Solute / Mass of Solution x 100 - **Mass by volume percentage of a solution**: Mass of Solute / Mass Volume of Solution x 100 - **Volume by volume percentage of a solution**: Volume of Solute / Volume of Solution x 100 # Suspension A suspension is a heterogeneous mixture where the solute particles don't dissolve but remain suspended in the bulk of the medium. They are visible to the naked eye. ## Properties of a Suspension - A suspension is a heterogeneous mixture. - The particles of a suspension can be seen by the naked eye. - The particles of a suspension scatter a beam of light passing through it and make its path visible. - The solute particles settle down when a suspension is left undisturbed, meaning a suspension is unstable. They can be separated from the mixture by the process of filtration. - When the particles settle down, the suspension breaks and it does not scatter light anymore. # Colloidal Solution A colloidal solution is a heterogeneous mixture. Examples include milk. Because of the small size of colloidal particles, we can't see them with the naked eye. However, these particles can easily scatter a beam of visible light, which is known as **The Tyndall Effect**. The scientist who discovered this effect is... **Example:** Sunlight passes through the canopy of a dense forest. In the forest, mist contains tiny droplets of water, which act as particles of colloid dispersed in air. ## Properties of a Colloid - A colloid is a heterogeneous mixture. - The size of particles of a colloid is too small to be individually seen by the naked eye. - Colloids are large enough to scatter a beam of light passing through them and make its path visible. - They do not settle down when left undisturbed, which means a colloid is quite stable. - They cannot be separated from the mixture by the process of filtration, but a special technique of separation known as centrifugation can be used to separate the colloidal particles. # Physical and Chemical Changes ## Physical Changes Physical changes are changes where no new substances are formed. They are called physical changes and these types of changes are reversible. **Example:** Melting of ice ## Chemical Changes The changes in which new substances are called chemical changes. Such changes are irreversible **Example:** Burning of a candle. Both chemical and physical changes take place.