Classify each of the following materials as an element, compound, heterogeneous mixture, or homogeneous mixture:
(a) air,
(b) water,
(c) diamond,
(d) soil.
The correct answer and explanation is :
Let’s classify each of the materials as an element, compound, heterogeneous mixture, or homogeneous mixture:
(a) Air
Classification: Homogeneous mixture
Explanation: Air is a mixture of gases, primarily nitrogen (about 78%), oxygen (about 21%), and trace amounts of argon, carbon dioxide, and other gases. Despite containing multiple components, air is considered a homogeneous mixture because its components are uniformly distributed at a molecular level, making it appear as a single substance. The gases do not separate into distinct layers, and they cannot be easily distinguished with the naked eye.
(b) Water
Classification: Compound
Explanation: Water (H₂O) is a compound because it is composed of two elements, hydrogen and oxygen, chemically bonded in a fixed ratio (two hydrogen atoms for every oxygen atom). The elements in water cannot be separated by physical means and exhibit different properties than the individual elements. Water is a pure substance with specific, consistent properties, such as its boiling point and freezing point.
(c) Diamond
Classification: Element
Explanation: Diamond is a pure form of carbon, a chemical element. It is made up entirely of carbon atoms arranged in a crystal lattice structure. Since diamond consists of only one type of atom, it is classified as an element. It is a solid at room temperature and exhibits distinct physical properties like hardness and transparency, which are unique to carbon in this particular structure. The carbon atoms in diamond are chemically bonded in a specific pattern that gives diamond its strength and clarity.
(d) Soil
Classification: Heterogeneous mixture
Explanation: Soil is a heterogeneous mixture because it consists of various components that can be easily distinguished from one another. These include minerals, organic matter (decaying plant and animal material), water, and air. The proportions of these components vary depending on the type of soil and its location. Since the components of soil are not uniformly distributed and can be separated by physical means (such as sifting or filtering), it is classified as a heterogeneous mixture.