States of matter: NECO Chemistry Past Questions and Answers

What the WAEC syllabus covers in States of matter

Our summary: The kinetic theory, changes of state and diffusion, the gas laws, and the properties of liquids, vapours and solids.

• Kinetic theory of matter ((1) Postulates of the kinetic theory of matter. (2) Use of the kinetic theory to explain the following processes: melting of solids, boiling of liquids, evaporation of liquids, dissolution of solutes, Brownian motion and diffusion.)
• Changes of state of matter ((1) Changes of state of matter should be explained in terms of movement of particles. It should be emphasized that randomness decreases (and orderliness increases) from gaseous state to liquid state and to solid state and vice versa. (2) Illustrations of changes of state using the different forms of water, iodine, sulphur, naphthalene etc. (3) Brownian motion to be illustrated using any of the following experiments: (a) pollen grains/powdered sulphur in water (viewed under a microscope); (b) smoke in a glass container illuminated by a strong light from the side; (c) a dusty room being swept and viewed from outside under sunlight.)
• Diffusion ((1) Experimental demonstration of diffusion of two gases. (2) Relationship between speed at which different gas particles move and the masses of particles. (3) Experimental demonstration of diffusion of solute particles in liquids.)
• Gases: characteristics and nature of gases (Arrangement of particles, density, shape and compressibility.)
• Gases: the gas laws (The gas laws: Charles'; Boyle's; Dalton's law of partial pressure; Graham's law of diffusion, Avogadro's law. The ideal gas equation of state. Qualitative explanation of each of the gas laws using the kinetic model. The use of kinetic molecular theory to explain changes in gas volumes, pressure, temperature. Mathematical relations of the gas law PV = nRT. Ideal and real gases. Factors responsible for the deviation of real gases from ideal situation.)
• Gases: laboratory preparation and properties of some gases ((1) Preparation of the following gases: H₂, NH₃ and CO₂. Principles of purification and collection of gases. (2) Physical and chemical properties of the gases.)
• Liquids (Characteristics and nature of liquids based on the arrangement of particles, shape, volume, compressibility, density and viscosity.)
• Vapour and gases ((1) Concept of vapour, vapour pressure, saturated vapour pressure, boiling and evaporation. (2) Distinction between vapour and gas. (3) Effect of vapour pressure on boiling points of liquids. (4) Boiling at reduced pressure.)
• Solids: characteristics and nature ((1) Ionic, metallic, covalent network and molecular solids. Examples in each case. (2) Arrangements of particles ions, molecules and atoms in the solid state.)
• Solids: types and structures (Relate the properties of solids to the type of interatomic and intermolecular bonding in the solids. Identification of the types of chemical bonds in graphite and differences in the physical properties.)
• Solids: properties of solids
• Structures, properties and uses of diamond and graphite (The uses of diamond and graphite related to the structure. The use of iodine in everyday life.)
• Determination of melting points of covalent solids (Melting points as indicator of purity of solids e.g. phenyl methanoic acid (benzoic acid), ethanedioic acid (oxalic) and ethanamide.)

Syllabus content © The West African Examinations Council (WASSCE (harmonised West African syllabus)). NECO questions are matched to the WAEC syllabus topic.