Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A mixture is a substance made by physically combining two or more elements or compounds in any proportion, where each component retains its individual chemical properties.
Homogeneous Mixtures: These have a uniform composition throughout. The components are not visible separately. Examples include salt dissolved in water or alloys like Brass ().
Heterogeneous Mixtures: These have a non-uniform composition. The components can often be seen with the naked eye or under a microscope. Examples include a mixture of sand and salt or oil and water.
Solute and Solvent: In a solution, the substance that is dissolved is called the solute (e.g., ), and the substance in which it is dissolved is the solvent (e.g., ).
Suspensions: A heterogeneous mixture containing large solid particles that settle down when left undisturbed (e.g., chalk powder in water).
Colloids: A type of mixture where the particle size is intermediate between a true solution and a suspension. They exhibit the Tyndall effect (scattering of light). Example: Milk.
Characteristics of Mixtures: They do not have a fixed melting or boiling point, no energy change (heat/light) occurs during formation, and components can be separated by physical methods like filtration, evaporation, or magnetic separation.
📐Formulae
💡Examples
Problem 1:
Identify the type of mixture formed when Iron filings () and Sulphur () powder are mixed together without heating.
Solution:
Heterogeneous Mixture.
Explanation:
Since the components are physically mixed and not chemically combined, the and particles remain distinct and can be separated using a magnet. The composition is not uniform throughout.
Problem 2:
Classify as a mixture or a compound.
Solution:
Homogeneous Mixture.
Explanation:
Air consists of gases like , , , and mixed physically. These gases retain their properties (e.g., still supports combustion) and their proportions can vary slightly depending on the location.
Problem 3:
What happens to the properties of compared to its constituent elements and ?
Solution:
The properties change completely because is a compound, not a mixture.
Explanation:
In a mixture, constituents retain their properties. However, is a compound where Hydrogen (, a combustible gas) and Oxygen (, a supporter of combustion) chemically react to form water (), which is a liquid used to extinguish fires.